REDACTED VERSION OF DOCUMENT SOUGHT TO BE SEALED Exhibit 21 Medco agrees to use commercially reasonable efforts to implement "full co-pay logic" for all Medco Plan Sponsors with respect to CVS as promptly as reasonably practicable. Pursuant to "full co-pay logic," the amount of any co-payment owed by a Covered Person for any prescription dispensed by CVS shall remain constant without regard to the fact that such co- payment may exceed the total amount of the reimbursement to be received by CVS for such prescription, except that if the co-payment exceeds CVS' usual and customary charge for such prescription, such usual and customary charge shall apply. Notwithstanding the foregoing, the parties acknowledge that Medco will implement full co-pay logic for Medco Plan Sponsors on a Medco Plan Sponsor by Medco Plan Sponsor basis in connection with renervals, new business and migration of the Medco Plan Sponsor to a new Medco Network and that such implementation is subject to negotiation with the applicable Medco Plan Sponsor. In the event that upon such renewal, new business or migration the Medco Plan Sponsor does not agree to implement full co-pay logic, Medco will add to the reimbursement payable to CVS hereunder $0.50 per brand name and generic drug prescription as an administration fee (unless CVS has agreed to waive the administration fee requirement for such Medco Plan Sponsor) to each such Medco Plan Sponsor as is necessary so that the aggregate number of retail prescriptions dispensed to Covered Persons of Medco Plan Sponsors that are either (i) not on full co-pay logic (excluding for purposes of this calculation those retail prescriptions dispensed to Covered Persons in any state in which Å¿ull co-pay logic is prohibited by applicable law or regulations), (ii) not paying the administration fee or (in) as to which CVS has no administration fee will not exceed twenty percent (20%) of the CVS/Medco Volume. Medco Plan Sponsors whose pharmacy benefit plans have percentage co-payments will be excluded for all purposes of this Section 2.6. At the request of CVS, Medco will inform CVS of the status under this Section of those Medco Plan Sponsors that have more than 100,000 Covered Persons; and in the event that, but only for so long as, Medco exceeds the 20% threshold described above, Medco will inform CVS of the new or renewed Medco Plan Sponsors to which Medco has added the administration fee.