42 C.F.R. § 136.32 – Disallowance.

(a) If it is determined that a hospital has submitted inaccurate information for payment, such as admission, discharge or billing data, an I/T/U may as appropriate—
1. (1) Deny payment (in whole or in part) with respect to any such services, and;
2. (2) Disallow costs previously paid, including any payments made under any methodology authorized under this subpart. The recovery of payments made in error may be taken by any method authorized by law.
(b) For cost based payments previously issued under this subpart, if it is determined that actual costs fall significantly below the computed rate actually paid, the computed rate may be retrospectively adjusted. The recovery of overpayments made as a result of the adjusted rate may be taken by any method authorized by law.