SECOND AMENDED AND RESTATED TAX SHARING AGREEMENT

Exhibit 10.51

SECOND AMENDED AND RESTATED TAX SHARING AGREEMENT

     The Amended and Restated Tax Sharing Agreement (the “ Agreement ”), dated as of January 1, 2006, by and between HLTH Corporation (formerly known as Emdeon Corporation), a Delaware corporation (“ HLTH ”), and WebMD Health Corp., a Delaware corporation (“ WebMD ”), is hereby amended and restated effective for taxable years beginning on and after January 1, 2008.

      WHEREAS , HLTH is the common parent corporation of an affiliated group of corporations (within the meaning of Section 1504(a) of the Internal Revenue Code of 1986, as amended (the “ Code ”));

      WHEREAS , WebMD and the WebMD Domestic Subsidiaries (as defined below) are members of the affiliated group of which HLTH is the common parent corporation;

      WHEREAS , WebMD made an initial public offering (the “ Offering ”) of its stock as contemplated by the Form S-1 filed with the Securities and Exchange Commission on May 12, 2005, as amended;

      WHEREAS , the Offering did not cause WebMD and the WebMD Domestic Subsidiaries to cease to be members of HLTH’s consolidated group for federal income tax purposes;

      WHEREAS , HLTH, WebMD and the WebMD Domestic Subsidiaries will continue to file consolidated federal income tax returns as required by Section 1501 of the Code (“Consolidated Federal Tax Returns”) and various members of the HLTH Group (as defined below) will continue to file consolidated, combined or unitary income tax returns in some states, municipalities and non-U.S. jurisdictions (“State, Local or Foreign Tax Returns”); and

      WHEREAS , HLTH, WebMD, the WebMD Domestic Subsidiaries and other members of the HLTH Group desire to agree upon a method for determining the financial consequences to each party resulting from the filing of a consolidated, combined or unitary income tax return; and

      NOW , THEREFORE , in consideration of the premises and mutual covenants herein contained, the parties hereby agree as follows:

1. DEFINITIONS.

     (a) For purposes of this Agreement, the terms set forth below shall have the following meanings.

          (i) “ Alternative Minimum Tax ” shall mean the tax imposed on corporations by Section 55 of the Code.

          (ii) “ Consolidated Federal Tax Liability ” shall mean, with respect to any taxable year, the Regular Tax and the Alternative Minimum Tax actually paid by the HLTH Group with respect to such taxable year (without taking into account any carry-backs of tax attributes from later taxable years).

          (iii) “ Federal Tax Liability ” of the WebMD Subgroup shall mean, with respect to any taxable year, an amount equal to the Consolidated Federal Tax Liability multiplied by a fraction, the numerator of which is the WebMD Subgroup’s Separate Return Tax Liability, and the denominator is the

sum of A) the WebMD Subgroup’s Separate Return Tax Liability and B) the HLTH Subgroup’s Separate Return Tax Liability.

          (iv) “ WebMD Domestic Subsidiary ” shall mean any WebMD Subsidiary that would be eligible, from time to time, to join with WebMD in the filing of a Consolidated Federal Tax Return, with WebMD as the common parent corporation, if WebMD and such WebMD Subsidiary were not members of the HLTH Group.

          (v) “ WebMD Subgroup ” shall be comprised of WebMD and the WebMD Subsidiaries.

          (vi) “ WebMD Subsidiary ” shall mean any corporation (as determined for tax purposes) that is controlled, directly or indirectly, by WebMD. For this purpose, “control” shall mean ownership of 50% or more of the stock or other equity interests in such corporations in terms of voting power or equity value.

          (vii) “ WebMD Tax Package ” means all information requested by HLTH, in a format determined by HLTH, in connection with a Consolidated Federal Tax Return of the HLTH Group or a State, Local or Foreign Tax Return that includes any member of the HLTH SubGroup and any member of the WebMD SubGroup. The WebMD Tax Package shall be prepared on a basis consistent with the past practices of the HLTH Group, or any relevant group of corporations with respect to any consolidated, combined or unitary State, Local or Foreign Tax Return.

          (viii) “ Regular Tax ” shall mean the tax imposed on corporations by Section 11 of the Code.

          (ix) “ Separate Return Tax Liability ” of the HLTH Subgroup or WebMD Subgroup shall mean, with respect to any taxable year, the liability for Regular Tax and Alternative Minimum Tax for such taxable year, and any interest, penalties, and other additions to such taxes for such taxable year, computed as if the HLTH Subgroup or the WebMD Subgroup, as the case may be, was not part of the HLTH Group for such taxable year, but rather was a separate affiliated group of corporations filing a Consolidated Federal Tax Return pursuant to Section 1501 of the Code. Such computation shall be made (A) without regard to the income, deductions (including net operating loss and capital loss deductions) and credits in any year of any member of the HLTH Group which is not a member of the relevant Subgroup, (B) with regard to net operating loss and capital loss carry-forwards from earlier years (but not carry-backs from later years except to the extent permitted by Section 2(g)) of the members of the relevant Subgroup; provided , however that no account shall be taken of any loss carryforward or other tax attribute of the WebMD Subgroup to the extent the WebMD Subgroup has previously received payment therefore pursuant to Section 2(iv) of this Agreement as it existed prior to its amendment pursuant to this Second Amended and Restated Tax Sharing Agreement, (C) with regard to the minimum tax credits of the relevant Subgroup, (D) as though the highest rate of tax specified in Section 11(b) of the Code were the only Regular Tax rate applicable to the relevant Subgroup and (E) consistent with the past practices of the HLTH Group; provided , however , that such computation can depart from the past practices of the HLTH Group in the event of a change in applicable Tax law or if HLTH is advised by its accountants or counsel that adherence to past practices would have an adverse effect on the HLTH Group. Transactions between the WebMD Subgroup and the HLTH Subgroup that are deferred under the Treasury regulations promulgated pursuant to Section 1502 of the Code shall also be deferred for purposes of this Agreement.

          (x) “Subgroup” shall mean the WebMD Subgroup or the HLTH Subgroup.

          (xi) “ HLTH Group ” shall mean HLTH, WebMD, the WebMD Domestic Subsidiaries

and any other corporation (as determined for tax purposes) that is controlled, directly or indirectly, by HLTH. For this purpose, “control” shall mean ownership of 50% or more of the stock or other equity interests in such corporation in terms of voting power or equity value.

          (xii) “ HLTH Subgroup ” shall be comprised of all members of the HLTH Group other than the members of the WebMD Subgroup.

     (b) For all purposes of this Agreement, unless the context otherwise requires, the definition of terms not defined herein shall be determined by reference to applicable law.

2. FEDERAL INCOME TAXES.

     (a)  References . All references in this Section 2 to taxes or matters related to taxes are references to federal income taxes and related federal income tax matters.

     (b)  Tax Sharing . With respect to any taxable year (or portion thereof, if applicable) of the WebMD Subgroup, WebMD shall pay to HLTH an amount equal to the WebMD Subgroup’s Federal Tax Liability.

     (c)  Estimated Payments . Not later than fifteen days prior to each date on which an estimated federal income tax installment is due (a “ Tax Payment Date ”), HLTH shall determine, and notify WebMD of, (i) the amount of the applicable required installment of the required annual payment of the HLTH Group under Section 6655(d) of the Code and (ii) the amount of such required installment calculated by reference to the estimated Federal Tax Liability of the WebMD Subgroup (such amount, the “ WebMD Subgroup Estimated Payment ”). WebMD shall then pay to HLTH, on or before the date which is three business days prior to such Tax Payment Date, the WebMD Subgroup Estimated Payment. The WebMD Subgroup Estimated Payment shall be computed in accordance with the past practices of the HLTH Group except in the event of a change in applicable Tax law, or if HLTH is advised by its accountants or counsel that adherence to past practices would have an adverse effect on the HLTH Group.

     (d)  Payment of Taxes at Year-End .

          (i) HLTH shall determine, and notify WebMD of, the WebMD Subgroup Payment within sixty days following the end of the taxable year for which such payment is to be made. On or before the date which is three business days prior to the last date prescribed by law for payment of the Consolidated Federal Tax Liability of the HLTH Group for such year, WebMD shall pay to HLTH an amount equal to the excess, if any, of the WebMD Subgroup’s Federal Tax Liability over the total WebMD Subgroup Estimated Payments made by WebMD with respect to such taxable year. A similar rule shall apply to the extent the amount of the WebMD Subgroup’s Federal Tax Liability is adjusted at or prior to the time at which the Consolidated Federal Tax Return for such year is filed.

          (ii) If the aggregate amount of the WebMD Subgroup Estimated Payments for a given taxable year is greater than the WebMD Subgroup’s Federal Tax Liability, HLTH shall promptly remit such excess amount to WebMD. A similar rule shall apply to the extent the amount of the WebMD Subgroup’s Federal Tax Liability is adjusted at or prior to the time at which the Consolidated Federal Tax Return for such year is filed.

          (iii) With respect to any Consolidated Federal Tax Return of the HLTH Group , except as described in subclause (iv) hereof (A) HLTH shall not reimburse WebMD for the tax savings attributable to the utilization of any net operating losses or other tax attributes of the WebMD Subgroup to offset federal income taxes of the HLTH Subgroup and (B) WebMD shall not reimburse HLTH for the

tax savings attributable to the utilization of any net operating losses or other tax attributes of HLTH or any other member of the HLTH Subgroup to offset federal incomes taxes of the WebMD Subgroup.

          (iv) In any tax year ending on or before December 31, 2007 in which the HLTH Subgroup has income or gain from the sale of assets (including a subsidiary) outside the ordinary course of business, extinguishment of debt or other extraordinary transaction (“Extraordinary Gains”), HLTH will make a payment to the WebMD Subgroup in an amount equal to 35% of the excess of (A) the amount of the loss carryforwards of the WebMD Subgroup actually absorbed by the HLTH Group in the computation of the Consolidated Federal Tax Liability for the year pursuant to Treas. Reg. Section 1.1502-21, over (B) the amount of the loss carryforwards of the WebMD Subgroup that would have been absorbed in the computation of the Consolidated Federal Tax Liability if such Extraordinary Gains had not been incurred by the HLTH Subgroup. Such payment shall be in full reimbursement for the tax savings (federal and state) attributable to the excess amount of loss carryf