TAX SHARING AGREEMENT

Exhibit 10.1

TAX SHARING AGREEMENT

dated as of December 31, 2001

between

USX Corporation

(to be renamed “Marathon Oil Corporation”)

and

United States Steel LLC

(to be renamed “United States Steel Corporation”)

TAX SHARING AGREEMENT

This TAX SHARING AGREEMENT is entered into as of December 31, 2001, by and among USX Corporation (“USX”) (to be renamed Marathon Oil Corporation), a Delaware corporation (together with its successors, “Marathon”) and United States Steel LLC (to be converted into a corporation named United States Steel Corporation), a Delaware limited liability company (together with its successors, “United States Steel”).

RECITALS

WHEREAS, pursuant to the tax laws of various jurisdictions, the affiliated group of which USX is the common parent files certain tax returns on a consolidated, combined, unitary, or other group basis;

WHEREAS, the Board of Directors of USX has determined that it is in the best interests of USX and its stockholders to effect a reorganization and distribute all of the outstanding shares of United States Steel Corporation to the holders of the USX-U. S. Steel Group common stock in complete redemption of such stock (the “Distribution”);

WHEREAS, in this Agreement, the parties have set forth certain representations and covenants that support the treatment of the Distribution as a transaction described in Section 355 of the Internal Revenue Code of 1986, as amended;

WHEREAS, in this Agreement, the parties have set forth the rights and obligations of Marathon and its affiliates and United States Steel and its affiliates with respect to the handling and allocation of certain Federal, state, local, foreign, and other taxes incurred in taxable periods beginning prior to the Distribution, and various other tax matters of the USX Consolidated Group;

WHEREAS, the allocation of certain Federal, state, local, foreign, and other taxes incurred in taxable periods beginning prior to the Distribution set forth in this Agreement shall incorporate, to the greatest extent possible, the tax sharing principles detailed in the USX Tax Allocation and Settlement Policy effective as of 1991 and as amended and restated as of August 26, 1997.

NOW, THEREFORE, in consideration of the mutual promises, covenants, and conditions contained herein, and intending to be legally bound hereby, the parties hereto agree as follows:

ARTICLE I

DEFINITIONS

SECTION 1.01. Definitions.

As used herein, the following terms shall have the following meanings:

“Agreement” shall mean this Tax Sharing Agreement dated as of December 31, 2001.

“Agreement and Plan of Reorganization” shall mean the Agreement and Plan of Reorganization dated as of July 31, 2001, by and among USX and United States Steel LLC.

“Business Day” shall mean a day other than a Saturday, Sunday or legal holiday (which for purposes of this Agreement shall include any day on which banks located in New York City are authorized or required by law to close).

“Calendar Day” shall mean each day of the week, including Saturdays, Sundays and legal holidays; provided that, if any action is required to be taken on a Saturday, Sunday or legal holiday, then such action shall be required to be taken on the immediately preceding Business Day.

“Code” shall mean the Internal Revenue Code of 1986, as amended.

“Combined State Tax” shall mean any State Tax, the return for which includes Tax Items of both the Marathon Stock Group and the United States Steel Stock Group.

“Consolidated Federal Tax” shall mean any Federal Tax, the return for which includes Tax Items of both the Marathon Stock Group and the United States Steel Stock Group.

“Delhi Stock Group” shall mean the USX-Delhi Group as presented for financial statement purposes under generally accepted accounting principles prior to the 1998 redemption of the USX—Delhi Group stock and shall include the financial position, results of operations and cash flows for the businesses of Delhi Gas Pipeline Corporation and certain other subsidiaries of USX and a portion of the corporate assets and liabilities and related transactions which are not separately identified with ongoing operating units of USX.

“Distribution” shall mean the distribution of the shares of United States Steel Corporation in complete redemption of all of the outstanding USX-U. S. Steel Group shares. The term “Distribution” shall have the same meaning herein as the term “Separation” has in the Agreement and Plan of Reorganization.

“Distribution Date” shall mean the day on which the Distribution is effected.

“Effective Realization (and the correlative terms, “Effectively Realized” and “Effectively Realizes”) shall mean, with respect to any Tax Attribute, the utilization of such Tax Attribute on a Tax Return of the USX Consolidated Group, the Marathon Tax Group, or the United States Steel Tax Group, including, but not limited to, the application of such Tax Attribute on an IRS Form 7004, on a final Tax Return (such as an IRS Form 1120), pursuant to a Final Determination for the relevant year, or pursuant to a Final Determination for a future or prior taxable period resulting in a carryback or carryforward to the relevant year.

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“Federal Tax” shall mean any Tax imposed under Subtitle A of the Code.

“Final Determination” (and the correlative term, “Finally Determined”) shall mean the final resolution of any Tax (or other tax-related matter) for a taxable period, including related interest or penalties, including (1) by the expiration of a statute of limitations or a period for the filing of claims for refunds, amending Tax Returns, appealing from adverse determinations or recovering any refund (including by offset), (2) by a decision, judgment, decree, or other order by a court of competent jurisdiction which has become final, (3) by a closing agreement or accepted offer in compromise under Sections 7121 or 7122 of the Code, or comparable agreements under the laws of other jurisdictions, (4) by execution of an IRS Form 870 or 870AD (or any successor IRS form) or by execution of a comparable form under the laws of other jurisdictions (notwithstanding that, with respect to a particular Tax Item for a particular taxable period, any such form may reserve — whether by its terms or by operation of law — the right of the taxpayer to file a claim for refund and/or the right of the Tax Authority to assert a further deficiency with respect to any such Tax Item for such period), or (5) by any allowance of a refund or credit, but only after the expiration of all periods during which such refund or credit may be recovered (including by way of offset).

“Group” shall mean either the United States Steel Stock Group or Marathon Stock Group, as the case may be.

“Holding Company Reorganization” shall mean the internal restructuring effectuated on July 2, 2001.

“Income Tax” shall mean any Tax based on, measured by, or computed by reference to gross income, gross receipts, net income, profits, or any other measure of income or profits.

“IRS” shall mean the United States Internal Revenue Service.

“Marathon Stock Group” shall mean the USX-Marathon Group as presented for financial statement purposes under generally accepted accounting principles prior to the Distribution and shall include the financial position, results of operations and cash flows for the businesses of Marathon Oil Company and certain other subsidiaries of USX and a portion of the corporate assets and liabilities and related transactions which are not separately identified with ongoing operating units of USX.

“Marathon Tax Group” shall mean the affiliated group of corporations as defined in section 1504 of the Code, or similar group of entities as defined under corresponding provisions of the laws of other jurisdictions, of which Marathon will be the common parent following the Distribution.

“Payroll Taxes” shall mean any Tax imposed on an employer in connection with the payment or provision of salaries or benefits and other remuneration to employees and directors, including income tax withholding, social security, unemployment taxes, and premiums for workers compensation.

“Penalties” shall mean any penalties, fines, additions to Taxes, or additional amounts imposed by any Tax Authority (domestic or foreign).

“Post-Distribution Period” shall mean any taxable period or portion thereof beginning after the Distribution Date.

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“Pre-Distribution Period” shall mean any taxable period or portion thereof ending on or before, or which includes, the Distribution Date.

“Ruling” shall mean (a) the private letter ruling issued by the IRS in connection with the Distribution (and any related transactions) or (b) any similar ruling issued by any Tax Authority other than the IRS in connection with the Distribution (and any related transactions).

“Ruling Documents” shall mean the request for the Ruling submitted to the IRS or to any other Tax Authority, together with the appendices and exhibits thereto and any supplemental filings or other materials subsequently submitted to the IRS or other Tax Authority, in connection with the Distribution (and any related transactions).

“SAR” shall mean any stock appreciation right.

“Separate State Tax” shall mean any State Tax other than a Combined State Tax.

“State Tax” shall mean any Tax payable to a state or local taxing jurisdiction of the United States.

“Supplemental Ruling” shall mean (a) any private letter ruling (other than the Ruling) issued by the IRS in connection with the Distribution (and any related transactions) or (b) any similar ruling (other than the Ruling) issued by any Tax Authority other than the IRS in connection with the Distribution (and any related transactions).

“Supplemental Ruling Documents” shall mean any request for a Supplemental Ruling submitted to the IRS or any other Tax Authority, together with the appendices and exhibits thereto and any supplemental filings or other materials subsequently submitted to the IRS or other Tax Authority, in connection with the Distribution (and any related transactions).

“Tax” shall mean any tax, charge, fee, impost, levy or other assessment, including, without limitation, all net income, gross receipts, capital, sales, use, ad valorem, value added, transfer, franchise, profits, inventory, capital stock, license, withholding, payroll, employment, social security, unemployment, excise, severance, stamp, occupation, property and estimated taxes, customs duties, fees, assessments and charges of any kind whatsoever and shall include any transferee liability in respect of such Taxes.

“Tax Attribute” shall mean any net operating losses, minimum tax credits, business tax credits, nonconventional fuels tax credits, net capital losses, charitable contributions, foreign income tax deductions, foreign income tax credits, or any similar Tax Item.

“Tax Authority” shall mean a governmental authority or any subdivision, agency, commission, or authority thereof or any quasi-governmental or private body having jurisdiction over the assessment, determination, collection or imposition of any Tax (including, without limitation, the IRS).

“Tax Item” shall mean any item of income, gain, loss, deduction or credit, or other similar item that may have the effect of increasing or decreasing any Tax.

“Tax Proceeding” shall mean any audit or other examination by any Tax Authority, assessment of Taxes, or proceeding or appeal of such a proceeding relating to Taxes, whether administrative or judicial.

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“Tax Return” shall mean any return, report, certificate, form, election, or similar statement or document (including, without limitation, estimated tax returns and reports, extension requests and forms, and information returns and reports), in each case as amended, required to be filed with any Tax Authority, Federal, state, or foreign, in connection with the determination, assessment or collection of any Tax or the administration of any laws, regulations, or administrative requirements relating to any Tax.

“Treasury Regulations” shall mean the final, temporary and proposed income tax regulations promulgated under the Code, as such regulations may be amended from time to time (including corresponding provisions of succeeding regulations).

“Two-Year Period” shall mean the period that begins on the Distribution Date and that ends on the date that is two years after the Distribution Date.

“United States Steel Stock Group” shall mean the USX-U. S. Steel Group as presented for financial statement purposes under generally accepted accounting principles prior to the Distribution and shall include the financial position, results of operations and cash flows for all businesses of USX other than the businesses, assets, and liabilities included in the Marathon Stock Group and a portion of the corporate assets and liabilities and related transactions which are not separately identified with ongoing operating units of USX.

“United States Steel Tax Group” shall mean the affiliated group of corporations as defined in section 1504 of the Code, or similar group of entities as defined under corresponding provisions of the laws of other jurisdictions, of which United States Steel will be the common parent following the Distribution.

“USX Consolidated Group” shall mean the group of entities that make up the affiliated group of corporations as defined in section 1504 of the Code, or similar group of entities as defined under corresponding provisions of the laws of other jurisdictions, of which USX, or a predecessor of USX under Treasury Regulations Section 1.1502-1(f)(4), is the common parent for all Pre-Distribution Periods.

“USX Headquarters Tax” shall mean any Tax (but not including Income Taxes) with respect to, or incurred by reason of, the corporate headquarters activities of USX or any member of the USX Consolidated Group that was allocated between the Marathon Stock Group and the United States Steel Stock Group for financial statement purposes prior to the Distribution.

“USX Shareholder” shall mean a holder of any class of USX stock on or before the Distribution Date, including shares of USX-U. S. Steel Group stock and shares of USX-Marathon Group stock.

SECTION 1.02. Terms Defined Elsewhere in this Agreement.

For the purposes of this Agreement, the following terms shall have the meanings set forth in the Sections indicated below:

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SECTION 1.03. Other Definitional Provisions.

(a) The words “hereof,” “herein,” “hereunder,” and words of similar import, when used in this Agreement, shall refer to this Agreement as a whole and not to any particular provision of this Agreement.

(b) The terms defined in the singular shall have a comparable meaning when used in the plural, and vice versa.

ARTICLE II

GENERAL

SECTION 2.01. Sole Tax Sharing Agreement.

This Agreement shall constitute the entire agreement between United States Steel and Marathon and their respective affiliates (including direct or indirect corporate subsidiaries, controlled partnerships, and controlled limited liability companies) with respect to the subject matters herein. The USX Tax Allocation and Settlement Policy effective as of 1991 and as amended and restated as of August 26, 1997 (including any amendments thereto) shall be or shall have been terminated as of the Distribution Date. On and after the Distribution Date, United States Steel and Marathon and their respective affiliates (including direct or indirect corporate subsidiaries, controlled partnerships, and controlled limited liability companies) shall have no rights or liabilities (including, without limitation, any rights and liabilities that may have accrued prior to the Distribution Date) under such terminated agreements and arrangements, and this Agreement shall be the sole tax sharing or tax allocation agreement among such corporations.

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SECTION 2.02. No Third Party Rights.

Nothing in this Agreement shall be interpreted to create any rights or liabilities (i) among members of the Marathon Tax Group, (ii) among members of the United States Steel Tax Group, (iii) between the Marathon Tax Group and any USX Shareholder, Marathon shareholder or United States Steel shareholder, or (iv) between the United States Steel Tax Group and any USX Shareholder, Marathon shareholder or United States Steel shareholder.

SECTION 2.03. Good Faith.

All parties shall act in good faith with respect to all aspects of this Agreement.

ARTICLE III

ADMINISTRATIVE AND COMPLIANCE MATTERS

SECTION 3.01. Designation Of Agent.

(a) Except with respect to Tax Returns described in Sections 3.02(a)(iii) and 3.02(a)(iv) of this Agreement, United States Steel hereby irrevocably authorizes and designates, and agrees to cause each member of the United States Steel Tax Group to so authorize and designate, Marathon as its sole and exclusive agent and attorney-in-fact to take such action (including execution of documents) as Marathon, in its sole discretion, may deem appropriate in any and all matters relating to Taxes (including Tax Proceedings) for taxable years or portions thereof in which United States Steel and its affiliates were members of the USX Consolidated Group. In exercising its authority under this Section 3.01, Marathon shall act in good faith and in a reasonable manner consistent with the principles of this Agreement.

(b) Marathon may, in its sole and absolute discretion, delegate at any time all or a portion of its authority, rights, or obligations under this Agreement to any corporation(s) or any person(s) (including, without limitation, United States Steel). Such delegation may be revoked by Marathon in its sole and absolute discretion.

SECTION 3.02. USX Consolidated Group Tax Returns and Elections.

(a) Original Tax Returns.

(i) Marathon shall prepare and file the Consolidated Federal Tax Returns and Combined State Tax Returns of the USX Consolidated Group for all Pre-Distribution Periods with the assistance of the members of the United States Steel Tax Group; provided that, all such Tax Returns shall be (1) prepared in a manner that is consistent with the most recent prior Tax Return of the USX Consolidated Group that includes the relevant position or is supported by a written opinion of outside tax counsel or nationally recognized accounting firm indicating that the position is more likely than not to prevail if litigated, unless the parties otherwise agree in writing; (2) prepared in a manner that is consistent with Article 6 of this Agreement and any Ruling, Supplemental Ruling, Ruling Documents, or Supplemental Ruling Documents; and (3) filed on a timely basis (taking into account applicable extensions); and further provided that, Marathon shall prepare any Tax Return that includes Combined State Taxes on a separate return basis or combined return basis, as the case may be, consistent with the manner in which such return was filed for the immediately preceding period.

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(A) Marathon shall consult with United States Steel, and United States Steel shall assist Marathon, in preparing the portions of any such Tax Returns relating directly to any Tax Items generated solely by, or allocated solely to, the United States Steel Stock Group. Notwithstanding the obligation to consult with United States Steel, but subject to United States Steel’s rights pursuant to Section 3.02(a)(i)(C) of this Agreement and subject to Section 3.02(c) of this Agreement, Marathon shall have the exclusive right to determine how the Tax Returns shall be prepared and filed, including, without limitation, the positions taken with respect to any Tax Item reported thereon, and how any elections shall be made thereon.

(B) Marathon shall provide drafts of all Tax Returns of the USX Consolidated Group to United States Steel, in the case of Federal income tax no later than 30 Calendar Days prior to the due date for filing such Tax Return (including all applicable extensions), and in the case of State Income Tax and all other Taxes no later than 15 Calendar Days prior to the due date for filing such Tax Returns (including all applicable extensions).

(C) If United States Steel requests that Marathon take a position relating to any Tax Item generated solely by, or allocated solely to, the United States Steel Stock Group (including a position with respect to the combined or separate status of a State Tax Return) that is (1) consistent with the most recent prior Tax Return of the USX Consolidated Group that includes the relevant position and (2) otherwise meets the requirements of Section 3.02(a)(i) of this Agreement, then Marathon shall reflect such position on the Tax Return. If United States Steel requests that Marathon take a position relating to any Tax Item generated solely by, or allocated solely to, the United States Steel Stock Group that is (1) supported by a written opinion of outside tax counsel or a nationally recognized accounting firm that the position is more likely than not to prevail in litigation (but does not meet the consistency requirements of the immediately preceding sentence) and (2) otherwise meets the requirements of Section 3.02(a)(i) of this Agreement, then Marathon may decline to take such position on the Tax Return; provided that, Marathon shall make to United States Steel a Buy-out Payment pursuant to Section 3.06 of this Agreement.

(ii) Marathon and the members of the Marathon Tax Group shall be solely responsible for the preparation and filing of (A) their respective Separate State Tax Returns for all taxable years, and (B) Tax Returns for the Marathon Tax Group for taxable years that begin after the Distribution Date.

(iii) United States Steel and the members of the United States Steel Tax Group shall be solely responsible for the preparation and filing of (A) their respective Separate State Tax Returns for all taxable years, and (B) Tax Returns for the United States Steel Tax Group for taxable years that begin after the Distribution Date.

(iv) All foreign Tax Returns shall be filed by the legal entities which had responsibility for filing such Tax Returns, regardless of whether such entities are members of the United States Steel Tax Group or the Marathon Tax Group after the Distribution.

(v) Without limiting the generality of Sections 8.01 and 8.02 of this Agreement, Marathon shall provide United States Steel, and United States Steel shall provide Marathon, with any information relevant or required for the preparation of the Tax Returns described in this Section 3.02. No later than June 30, 2002, Marathon shall provide United States Steel with a list of all Consolidated Federal Tax Returns and Combined State Tax Returns that Marathon will file pursuant to Section 3.02(a) of this Agreement.

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(b) Amended Tax Returns, Claims for Refunds, and Tentative Carryback Adjustments.

(i) Marathon shall prepare and file any amended Tax Return, claim for refund, or tentative carryback adjustment (including an IRS Form 1139 arising as a result of an election made pursuant to Section 3.02(c)(ii) of this Agreement involving a Tax Item of the United States Steel Tax Group arising in a Post-Distribution Period) affecting a Tax Item included, or to be included, on any Consolidated Federal Tax Return or Combined State Tax Return of the USX Consolidated Group; provided that, all such amended Tax Returns, claims for refund, or tentative carryback adjustment shall (A) be prepared in a manner that is consistent with Article 6 of this Agreement and any Ruling, Supplemental Ruling, Ruling Documents, or Supplemental Ruling Documents, (B) meet the requirements of Section 3.02(c) of this Agreement, and (C) be filed on a timely basis (taking into account applicable extensions).

(ii) Marathon shall provide to United States Steel for its review any amended Tax Return, claim for refund, or tentative carryback adjustment of the USX Consolidated Group no later than 30 Calendar Days prior to its filing. Within 25 Calendar Days of receiving from Marathon such amended Tax Return, claim for refund, or tentative carryback adjustment, United States Steel shall have the right to request that Marathon not take any position proposed to be taken on such amended Tax Return, claim for refund, or tentative carryback adjustment relating to any Tax Item generated by (in whole or in part), or allocated to (in whole or in part), the Marathon Stock Group, and Marathon shall not take such position on an amended Tax Return, claim for refund, or tentative carryback; provided that, United States Steel shall make to Marathon a Buy-out Payment pursuant to Section 3.06 of this Agreement.

(iii) United States Steel shall have the right to request that Marathon file an amended Tax Return, claim for refund, or tentative carryback adjustment relating to any Tax Item generated solely by, or allocated solely to, the United States Steel Stock Group; provided that, all such amended Tax Returns, claims for refund, or tentative carryback adjustments shall satisfy the requirements of Section 3.02(b)(i) of this Agreement. United States Steel shall submit such portion of the amended Tax Return, claim for refund, or tentative carryback adjustment to Marathon no later than 30 Calendar Days prior to the due date for filing such amended Tax Returns, claims for refund, or tentative carryback adjustments and Marathon shall either (A) file such amended Tax Return, claim for refund, or tentative carryback adjustment within 25 Calendar Days of receiving it from United States Steel or (B) exercise its buy-out right provided in the next sentence. Marathon may, in its sole and absolute discretion, decline to take any position proposed to be taken on such amended Tax Return, claim for refund, or tentative carryback adjustment relating to any Tax Item generated solely by, or allocated solely to, the United States Steel Stock Group; provided that, if such position otherwise satisfies the requirements of this Section 3.02(b)(iii), then Marathon shall make to United States Steel a Buy-out Payment pursuant to Section 3.06 of this Agreement.

(c) Elections.

(i) Consistency. Any election that affects the Tax Items of both the Marathon Stock Group and the United States Steel Stock Group shall be made consistent with the most recently filed original Tax Return, unless the parties otherwise agree or the party seeking to make the inconsistent election makes a Buy-out Payment to the other party pursuant to Section 3.06 (for purposes of applying section 3.06, any such election shall be treated as a position with respect to all affected Tax Items).

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(ii) Carryback of Post-Distribution Period United States Steel Losses and Credits. Subject to the standards for filing Tax Returns of the USX Consolidated Group set forth in Sections 3.02(a) and 3.02(b) of this Agreement, United States Steel may elect to carry back any Post-Distribution Period losses or credits of the United States Steel Tax Group that may be carried back to a Tax Return of the USX Consolidated Group under any pertinent section of the Treasury Regulations, and Marathon shall take any such election into account in preparing the relevant Tax Returns, including amended Tax Returns if necessary, of the USX Consolidated Group.

(iii) Marathon may, at its option, elect, and the United States Steel Tax Group shall join it in electing (if necessary), to ratably allocate Tax Items (other than extraordinary Tax Items) of the United States Steel Stock Group in accordance with the relevant provisions of Treasury Regulations Section 1.1502-76. If Marathon makes such an election, the members of the United States Steel Tax Group shall provide to Marathon such statements as are required under the Treasury Regulations and other appropriate assistance.

(iv) Marathon shall elect, and the United States Steel Tax Group shall join it in electing (if necessary), to reattribute any net operating loss or capital loss carryover of a member of the United States Steel Stock Group to USX in accordance with the relevant provisions of Treasury Regulations Section 1.1502-20(g). The members of the United States Steel Tax Group shall provide to Marathon such statements as are required under the Treasury Regulations and other appropriate assistance.

SECTION 3.03. USX Consolidated Group Tax Proceedings.

(a) Control Over Tax Proceedings.

Subject to the limitations set forth below in this Section 3.03, Marathon shall have the exclusive right to control, contest, and represent the interests of United States Steel and each member of the United States Steel Tax Group in any Tax Proceeding relating to any Tax Item included on a Consolidated Federal Tax Return or Combined State Tax Return for all Pre-Distribution Periods, including the right to resolve, settle, or agree to any deficiency, claim or adjustment proposed, asserted, or assessed, in connection with or as a result of any such Tax Proceeding, and including the right to execute waivers, choose the forum for contests, schedule conferences, and resolve or settle any Tax Item.

(b) United States Steel Participation Rights.

Marathon shall consult with United States Steel, and United States Steel shall have the right (i) to represent the interests of itself and each member of the United States Steel Tax Group, in any Tax Proceeding relating to any Tax Item generated solely by, or allocated solely to, the United States Steel Stock Group, and (ii) to contest, resolve, settle, or agree to any deficiency, claim, or adjustment proposed, asserted, or assessed in connection with or as a result of such Tax Proceeding; provided that, the entering into of any such resolution, settlement, or agreement or any decision in connection with (including the entering into of) any judicial or administrative proceeding relating to Taxes shall be subject to the review and approval of Marathon which approval shall not be unreasonably withheld. Notwithstanding the preceding sentence, Marathon shall have the exclusive right to represent the interests of United States Steel and each member of the United States Steel Tax Group in any Tax Proceeding with respect to any Tax Items that are allocated to both the Marathon Stock Group and the United

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States Steel Stock Group; provided that, Marathon shall exercise this authority under this Section 3.03(b) without discriminating against United States Steel or any member of the United States Steel Tax Group unless Marathon makes to United States Steel a Buy-out Payment pursuant to Section 3.06 of this Agreement.

(c) Marathon Buy-Out Right.

Notwithstanding Section 3.03(b) of this Agreement, Marathon shall have the right to concede, resolve, or settle any Tax Proceeding relating to any Tax Item generated by (in whole or in part), or allocated to (in whole or in part), the United States Steel Stock Group without the consent of United States Steel or any member of the United States Steel Tax Group; provided that, Marathon shall make to United States Steel a Buy-out Payment pursuant to Section 3.06 of this Agreement.

(d) United States Steel Buy-Out Right.

Notwithstanding Section 3.03(a) of this Agreement, United States Steel shall have the right to request that Marathon concede, resolve, or settle any Tax Proceeding relating to any Tax Item generated by (in whole or in part), or allocated to (in whole or in part), the Marathon Stock Group, and Marathon shall be required to so concede, resolve, or settle such Tax Proceeding; provided that, United States Steel shall make to Marathon a Buy-out Payment pursuant to Section 3.06 of this Agreement.

(e) Alternative Method for Administrative Resolution of Tax Proceedings.

Notwithstanding Sections 3.03(a), 3.03(b), 3.03(c), and 3.03(d) of this Agreement, Marathon and United States Steel may mutually agree to resolve with the relevant Tax Authority any proposed adjustments to a Tax Return of the USX Consolidated Group in any manner mutually agreed to by Marathon and United States Steel (including settling any Tax Proceeding on a basis that benefits one Group to the detriment of the other), and may take any action consistent with this Agreement to facilitate such settlement (including payment from one Group to the other).

(f) Judicial Resolution of Tax Proceedings.

In the event that any proposed adjustments to Tax Items of the USX Consolidated Group are not resolved administratively and a judicial resolution is necessary, Marathon and United States Steel shall consult regarding the choice of litigation forum and may agree to choose any available forum, which, as of the date of this Agreement, are the United States Tax Court, the United States Court of Federal Claims, the United States district court with jurisdiction over the relevant Federal Tax Return, or a state court with jurisdiction over the relevant State Tax Return. If Marathon and United States Steel agree that the jurisdiction of a refund forum should be obtained, United States Steel shall make any payments required pursuant to Section 5.02(d) of this Agreement. If Marathon and United States Steel are unable to reach agreement as to the choice of litigation forum for any Federal tax matter, the United States Tax Court shall be selected as the litigation forum.

SECTION 3.04. Notices from Tax Authorities.

(a) If any member of the Marathon Tax Group receives written notice of, or relating to, a Tax Proceeding from a Tax Authority that asserts, proposes or recommends a deficiency, claim, or adjustment that, if sustained, would result in the redetermination of a Tax Item of a member of

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the United States Steel Stock Group, Marathon shall promptly provide a copy of such notice to United States Steel (but in no event later than ten Calendar Days following the receipt of such notice). If any member of the United States Steel Tax Group receives written notice of, or relating to, a Tax Proceeding from a Tax Authority that asserts, proposes or recommends a deficiency, claim, or adjustment that, if sustained, would result in the redetermination of a Tax Item of a member of the Marathon Stock Group, United States Steel shall promptly provide a copy of such notice to Marathon (but in no event later than ten Calendar Days following the receipt of such notice).

(b) Without limiting the generality of Section 12.04(b) of this Agreement, the failure of Marathon or United States Steel to promptly notify the other of any matter relating to a particular Tax for a taxable period shall not relieve the other party of any liability and/or obligation which it may have under this Agreement with respect to such Tax for such taxable period except to the extent that such other party’s rights hereunder are materially prejudiced by such failure. The remedy for such failure shall be determined pursuant to Section 12.05 of this Agreement.

SECTION 3.05. Supplemental Rulings.

(a) Marathon shall have the right to obtain a Supplemental Ruling in its sole and exclusive discretion. If Marathon decides to obtain a Supplemental Ruling, United States Steel shall cooperate with Marathon and take any and all actions reasonably requested by Marathon in connection with obtaining the Supplemental Ruling (including, without limitation, by making any representation or covenant or providing any materials or information requested by any Tax Authority; provided that, United States Steel shall not be required to make any representation or covenant that is inconsistent with facts or as to future matters or events over which it has no control). In connection with obtaining a Supplemental Ruling (i) Marathon shall cooperate with and keep United States Steel informed in a timely manner of all material actions taken or proposed to be taken by Marathon in connection therewith; (ii) Marathon shall (A) reasonably in advance of the submission of any Supplemental Ruling Documents, provide United States Steel with a draft copy thereof; (B) reasonably consider United States Steel’s comments on such draft copy; and (C) provide United States Steel with a final copy of all Supplemental Ruling Documents; and (iii) Marathon shall provide United States Steel with notice reasonably in advance of, and United States Steel shall have the right to attend, any formally scheduled meetings with any Tax Authority (subject to the approval of the Tax Authority) that relate to such Supplemental Ruling. Further, Marathon shall provide United States Steel with 30 Calendar Days to review such Supplemental Ruling under this Section 3.05(a) and shall not file such request prior to the expiration of 30 Calendar Days unless United States Steel agrees to such early filing in writing. Marathon shall bear all costs and expenses incurred in obtaining such Supplemental Ruling and shall reimburse United States Steel for all reasonable costs and expenses of outside third parties incurred by United States Steel in connection with obtaining a Supplemental Ruling requested by Marathon.

(b) United States Steel hereby agrees that Marathon shall have, subject to Section 3.05(a) of this Agreement, sole and exclusive control over the process of obtaining a Supplemental Ruling and that only Marathon shall apply for a Supplemental Ruling. United States Steel further agrees that it shall not seek any guidance from the IRS or any other Tax Authority concerning the Distribution, except as set forth in Section 3.05(c) of this Agreement.

(c) Marathon agrees that at the reasonable request of United States Steel, Marathon shall cooperate with United States Steel and use its reasonable efforts to seek to obtain, as

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expeditiously as possible, a Supplemental Ruling or other guidance from the IRS or any other Tax Authority for the purpose of confirming (i) the Ruling or any Supplemental Ruling issued previously and (ii) compliance on the part of United States Steel or any member of the United States Steel Tax Group with its obligations under this Agreement. United States Steel shall reimburse Marathon for all reasonable costs and expenses incurred by Marathon in connection with obtaining a Supplemental Ruling requested by United States Steel.

SECTION 3.06. Buy-out Payments.

(a) In General. Any payment made pursuant to this Section 3.06 (a “Buy-out Payment”) shall be determined as follows.

(b) Buy-out Payments by Marathon.

(i) Amount of Buy-out Payment.

The amount of a Buy-out Payment shall be determined by the parties. If the parties are unable to agree on the amount of a Buy-out Payment within 30 Calendar Days from the time that the position which Marathon declines to take is proposed by United States Steel, and United States Steel does not withdraw its request and Marathon does not agree to take the position proposed (and the time available for taking such position has not expired), then the amount shall be determined pursuant to Dispute Resolution as provided in Section 11.01 of this Agreement in accordance with the following principles:

(A) The amount shall reflect the extent to which each party has acted in good faith with respect to the position proposed by United States Steel; and

(B) The amount shall reflect the total benefit that would have been realized for all relevant taxable years by United States Steel had the position proposed by it been taken, including changes to the Separate Return Liability of United States Steel, payments from and to Marathon pursuant to Section 5.03 of this Agreement, Federal Tax interest savings and costs which would have been allocated to United States Steel, and the likelihood that any such benefits projected to be realized in future years in fact would have been received; and

(C) The amount shall reflect the relative likelihood that the position proposed by United States Steel would have prevailed in litigation; and

(D) The amount shall reflect the time when the benefits would have been realized by United States Steel giving due regard to whether the position would have been taken on an original return or at some other time.

Upon a determination that a party has not acted in good faith, the amount may be reduced (but not below zero ($0)) and/or costs may be awarded as appropriate.

(ii) When Buy-out Payments are to be Made.

Unless the parties otherwise agree, a Buy-out Payment shall be made within 30 Calendar Days of the time when United States Steel would have received the relevant benefit if Marathon had agreed to pursue the position proposed by United States Steel. If the amount of a Buy-out Payment is determined pursuant to Dispute Resolution, Marathon shall make such Buy-out Payment no later than 30 Calendar Days following the conclusion of such Dispute Resolution, and if such payment date occurs prior to, or subsequent to, the date on which United States

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Steel would have realized the benefit from the proposed position, then the amount of the Buy-out Payment shall reflect interest from the time such benefit would have been realized until the actual payment date.

(iii) Tax Item Deemed Transferred.

If Marathon makes a Buy-out Payment with respect to a Tax Item generated by, or allocated to, the United States Steel Stock Group, such Tax Item thereafter shall be treated as a Tax Item allocated to the Marathon Stock Group for all purposes of this Agreement in all relevant taxable periods.

(c) Buy-out Payments By United States Steel.

The provisions of Section 3.06(b) of this Agreement shall be applied with respect to any Buy-out Payment by United States Steel by substituting “United States Steel” for “Marathon” each place that it appears and by substituting “Marathon” for “United States Steel” each place that it appears.

ARTICLE IV

DETERMINATION OF EACH GROUP’S SHARE OF THE USX CONSOLIDATED

GROUP’S TAX LIABILITY AND TAX ATTRIBUTES

SECTION 4.01. General.

(a) While the provisions of this Article 4 are intended to reflect the principles of the USX Tax Allocation and Settlement Policy effective as of 1991 and as amended and restated as of August 26, 1997, that policy shall have been revoked in its entirety as provided in Section 2.01 of this Agreement and the provisions of this Article 4 shall control. The principles of this Article 4 shall be applied in all relevant years as if there were two Groups, the Marathon Stock Group and the United States Steel Stock Group, and all Tax Items of the Delhi Stock Group shall be allocated to the Marathon Stock Group and the United States Steel Stock Group as provided in Section 4.02(a)(i)(E) of this Agreement. The determination under this Article 4 of a Group’s allocable share of the tax liability of the USX Consolidated Group shall be made for the year to which the adjustment relates rather than for the current year.

(b) The entire determination required under this Article 4 shall be made whenever it is necessary to determine each Group’s share of any tax liability of the USX Consolidated Group for any Pre-Distribution Period.

(c) Given the uncertain effects of various Tax Items on the total liability of the USX Consolidated Group, it is understood that a certain amount of judgment will be necessary to apply this Article 4 and that both Marathon and United States Steel will act reasonably and in good faith when applying the principles of this Article 4.

SECTION 4.02. Determination of Each Group’s Allocable Share of the Federal Tax Liability of the USX Consolidated Group and Resulting Tax Attributes.

If the USX Consolidated Group is a regular taxpayer in the relevant period, each Group’s share of the regular Federal income tax liability of the USX Consolidated Group and resulting Tax Attributes shall be determined under Section 4.02(a) of this Agreement; if the USX Consolidated Group is an alternative minimum taxpayer in the relevant period, each Group’s share of the alternative minimum tax liability of the USX Consolidated Group and resulting Tax Attributes shall be determined under Section 4.02(b) of this Agreement.

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(a) Determination of Groups’ Allocable Share if the USX Consolidated Group is a Regular Taxpayer in the Relevant Period.

Each Group’s allocable share of the regular Federal income tax liability of the USX Consolidated Group (“Total USX Liability”) shall be determined by calculating the Group’s Separate Return Liability pursuant to Section 4.02(a)(i) and then adjusting for the effects of the Consolidated Federal Tax Return of the USX Consolidated Group pursuant to Section 4.02(a)(ii). Each Group’s share of the resulting Tax Attributes shall be determined by application of Section 4.02(a)(iii).

(i) Groups’ Separate Return Liability.

The Federal regular income tax liability of the United States Steel Stock Group and the Marathon Stock Group (the “Separate Return Liability”) shall be determined as if each Group were filing its own separate consolidated return (the “Separate Return Basis”). Without limiting the generality of the foregoing statement, the following special rules shall apply:

(A) For purposes of determining the Separate Return Liability of each Group, the taxable income or loss of each Group shall be the income or loss of each Group for financial statement purposes adjusted as shown on an IRS Form Schedule M associated with such Group. Any item of income or expense that is allocated between the Groups for financial statement purposes shall be allocated in a manner consistent with such financial statements in order to compute taxable income or loss on a Separate Return Basis.

(B) Dividend Income. For purposes of determining the Separate Return Liability of each Group, the tax treatment of any dividend income received by a Group shall be consistent with the actual tax consequences in the Tax Returns of the USX Consolidated Group.

(C) Tax Elections. All tax elections, which must be made on a consolidated return basis, shall conform to those elected by the USX Consolidated Group.

(D) Income Taxes relating to Holding Company Reorganization and Distribution.

(1) In the event that the USX Consolidated Group recognizes gain or other income as a result of the Holding Company Reorganization or Distribution being taxable due to the breach of a covenant or representation in Article 6 of this Agreement by a member of the United States Steel Tax Group or an acquisition of United States Steel that violates Section 355(e) of the Code, the United States Steel Stock Group shall be allocated such gain or other income. No portion of such gain or other income shall be allocated to the Marathon Stock Group.

(2) In the event that the USX Consolidated Group recognizes gain or other income as a result of the Holding Company Reorganization or Distribution being taxable due to the breach of a covenant or representation in Article 6 of this Agreement by a member of the Marathon Tax Group or an acquisition of Marathon that violates Section 355(e) of the Code, the Marathon Stock Group shall be allocated such gain or other income. No portion of such gain or other income shall be allocated to the United States Steel Stock Group.

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(3) In the event that the USX Consolidated Group recognizes gain or other income as a result of the Holding Company Reorganization or Distribution being taxable due to an acquisition that violates Section 355(e) of the Code, and both United States Steel and Marathon have been acquired in transactions that are presumed to violate Section 355(e) of the Code (e.g., transactions that involve acquisitions by a third party of 50 percent or more of the stock of the relevant corporation), then such gain or other income shall be allocated to the Group whose acquisition occurred first in time (based on closing date). In the event that the USX Consolidated Group recognizes gain or other income as a result of the Holding Company Reorganization or Distribution being taxable under any other provision of the Code due to the breach of a covenant or representation in Article 6 of this Agreement, and both United States Steel and Marathon have breached a covenant or representation in Article 6 of this Agreement, then such gain or other income shall be allocated to the Group whose action causing such breach occurred first in time. No portion of such gain or other income shall be allocated to the other Group. Notwithstanding the foregoing, if the Distribution is characterized as other than a distribution of the stock of United States Steel and both United States Steel and Marathon (I) have been acquired in transactions that are presumed to violate Section 355(e) of the Code (e.g., transactions that involve acquisitions by a third party of 50 percent or more of the stock of the relevant corporation) or (II) have breached a covenant or representation in Article 6 of this Agreement, then any gain or other income recognized as a result of the Holding Company Reorganization or Distribution being taxable under any provision of the Code shall be allocated to the Group with respect to which such gain or other income is recognized.

(4) In the event that the USX Consolidated Group recognizes gain or other income as a result of the Holding Company Reorganization or Distribution being taxable, and no covenant or representation in Article 6 of this Agreement has been breached and neither United States Steel nor Marathon has been acquired in a transaction that is presumed to violate Section 355(e) of the Code, then any gain or other income shall be allocated to the Group with respect to which such gain or other income is recognized.

(E) Taxes Relating to Sale of Delhi Stock Group. In the event that the tax liability of the USX Consolidated Group is adjusted as a result of an adjustment to the taxable gain or loss on the sale of the Delhi Stock Group or as the result of adjustments to Tax Items allocated to entities within the Delhi Stock Group, the United States Steel Stock Group’s share of such tax liability shall be 39%. The Marathon Stock Group’s share shall be the remaining portion.

(F) Excess Loss Accounts and Deferred Intercompany Gains. Any tax liability resulting from the existence of any excess loss accounts or deferred intercompany gains immediately before the Distribution shall be allocated to the Group to which it relates and shall not be treated as a Tax relating to the Distribution under Section 4.02(a)(i)(D) of this Agreement. For purposes of this Agreement, an excess loss account shall relate to the Group which immediately before the Distribution owned the stock to which such excess loss account was attributable, and a deferred intercompany gain shall relate to the Group which immediately before the Distribution owned the entity whose gain was deferred.

(G) Offsets to Refund Claims. Any tax liability that otherwise would be precluded by the relevant statute of limitations which is applied as an offset to a refund claim shall be allocated to the Group whose Tax Items are included on such refund claim. In the event that a refund claim is filed which includes Tax Items of both Groups, any such offsets shall be allocated first to the Group whose Tax Items generated such offset and then to the other Group.

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Example 1.

Assumptions. For the year at issue, the USX Consolidated Group files a claim for refund totaling $10 million, of which $8 million is attributable to Tax Items generated by, or allocated to, the United States Steel Stock Group and $2 million is attributable to Tax Items generated by, or allocated to, the Marathon Stock Group. The Tax Authority has an offset in the amount of $1 million, which is attributable entirely to Tax Items generated by, or allocated to, the Marathon Stock Group. The USX Consolidated Group receives a $9 million refund.

Allocation. The offset is allocated to the Marathon Stock Group and reduces the portion of the refund allocated to Marathon to $1 million. Of the $9 million refund received by the USX Consolidated Group, $8 million is allocated to the United States Steel Stock Group and $1 million is allocated to the Marathon Stock Group.

Example 2.

Assumptions. For the year at issue, the USX Consolidated Group files a claim for refund totaling $10 million, of which $8 million is attributable to Tax Items generated by, or allocated to, the United States Steel Stock Group and $2 million is attributable to Tax Items generated by, or allocated to, the Marathon Stock Group. The Tax Authority has offsets totaling $4 million, which are attributable entirely to Tax Items generated by, or allocated to, the Marathon Stock Group. The USX Consolidated Group receives a $6 million refund.

Allocation. The offset is allocated first to the Marathon Stock Group and reduces the portion of the refund allocated to Marathon to $0. The offset is thereafter allocated to the United States Steel Stock Group, and reduces the refund allocated to the United States Steel Stock Group to $6 million.

(H) Carryback of Post-Distribution United States Steel Losses and Credits. Any carryback of losses or credits of the United States Steel Tax Group to the Tax Returns of the USX Consolidated Group pursuant to an election described in Section 3.02(c)(ii) of this Agreement shall, for all purposes of this Agreement, be treated as a Tax Attribute of the United States Steel Stock Group.

(ii) Adjustments To Group’s Separate Return Liability For Regular Tax Effects Of Consolidated Group.

The Separate Return Liability of each Group determined pursuant to Section 4.02(a)(i) of this Agreement shall be adjusted for the regular tax effects of the USX Consolidated Group as follows:

(A) The Total USX Liability shall be determined for regular tax purposes, taking into account the effects of any carryforward or carryback of Tax Attributes from prior or future years, including the effects of any carrybacks from a Tax Return for a Post-Distribution Period of the United States Steel Tax Group carried back pursuant to Section 4.02(a)(i)(H) of this Agreement.

(B) The Separate Return Liabilities of each Group determined pursuant to Section 4.02(a)(i) of this Agreement shall be combined (the “Combined Separate Return Liabilities”). The Combined Separate Return Liabilities shall be subtracted from the Total USX Liability to determine the aggregate net benefit or detriment of filing a Consolidated Federal Income Tax Return (the “Consolidated Return Benefit or Detriment”).

(C) The Consolidated Return Benefit or Detriment shall be allocated to the Group whose Tax Attributes caused the benefit or detriment. Such allocation shall be consistent with the actual usage of the Tax Attributes on the Tax Returns of the USX Consolidated Group. Without limiting the generality of the foregoing statement, the following special rules shall apply:

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(1) For these purposes, Tax Attributes shall be deemed to cause a benefit to the extent that such Tax Attributes are used on the Tax Returns of the USX Consolidated Group but are not used by a Group on a Separate Return Basis; Tax Attributes shall be deemed to cause a detriment to the extent that such Tax Attributes are used by a Group on a Separate Return Basis but are not used on the Tax Returns of the USX Consolidated Group (except where preemption by the other Group’s Tax Attributes occurs as set forth in Section 4.02(a)(iii) of this Agreement). Thus, the effect of a statutory limitation on the use of a Group’s Tax Attribute on a Tax Return of the USX Consolidated Group shall be disregarded even if the statutory limitation is attributable to Tax Items of the other Group.

Example.

Assumptions. The Marathon Stock Group generates a $100 foreign tax credit that is used for purposes of computing the Separate Return Liability of the Marathon Stock Group for such year. The United States Steel Stock Group generates $100 of interest expense that is used in its entirety to compute the Separate Return Liability of the United States Steel Stock Group for the year and decreases the amount of the USX Consolidated Group’s foreign source income. As a result of such interest expense, only $50 of the Marathon Stock Group’s foreign tax credits is used in such year.

Allocation. For purposes of allocating any net Consolidated Return Benefit or Detriment, the United States Steel Group’s $100 of interest expense shall be treated as being used on the Tax Returns of the USX Consolidated Group and only $50 of the Marathon Stock Group’s foreign tax credits shall be treated as being used on the Tax Returns of the USX Consolidated Group.

(2) To determine the utilization of each Group’s share of a particular Tax Attribute when the amount of such Tax Attribute available exceeds the total amount of such Tax Attribute capable of being utilized on the Tax Return of the USX Consolidated Group (the “Consolidated Tax Attribute”), each Group’s portion of the Consolidated Tax Attribute shall be an amount which bears the same ratio to the Consolidated Tax Attribute utilized as the amount of each Group’s available Tax Attrib