Improper payment means:
(1) Any payment that should not have been made or that was made in an incorrect amount under statutory, contractual, administrative, or other legally applicable requirements.
(i) Incorrect amounts are overpayments or underpayments that are made to eligible recipients (including inappropriate denials of payment or service, any payment that does not account for credit for applicable discounts, payments that are for an incorrect amount, and duplicate payments). An improper payment also includes any payment that was made to an ineligible recipient or for an ineligible good or service, or payments for goods or services not received (except for such payments authorized by law).
2 CFR § 200.1
These are the definitions for terms used in this part. Different definitions may be found in Federal statutes or regulations that apply more specifically to particular programs or activities. These definitions could be supplemented by additional instructional information provided in governmentwide standard information collections. For purposes of this part, the following definitions apply: