42 CFR §411.22

1. (a)A primary payer, and an entity that receives payment from a primary payer, must reimburse CMS for any payment if it is demonstrated that the primary payer has or had a responsibility to make payment.
2. (b)A primary payer's responsibility for payment may be demonstrated by—
   1. (1)A judgment;
   2. (2)A payment conditioned upon the recipient's compromise, waiver, or release (whether or not there is a determination or admission of liability) of payment for items or services included in a claim against the primary payer or the primary payer's insured; or
   3. (3)By other means, including but not limited to a settlement, award, or contractual obligation.
3. (c)The primary payer must make payment to either of the following:
   1. (1)To the entity designated to receive repayments if the demonstration of primary payer responsibilities is other than receipt of a recovery demand letter from CMS or designated contractor.
   2. (2)As directed in a recovery demand letter.