improper payment
(4) Improper payment .— The term “improper payment”— (A) means any payment that should not have been made or that was made in an incorrect amount, including an overpayment or underpayment, under a statutory, contractual, administrative, or other legally applicable requirement; and (B) includes— (i) any payment to an ineligible recipient; (ii) any payment for an ineligible good or service; (iii) any duplicate payment; (iv) any payment for a good or service not received, except for those payments where authorized by law; and (v) any payment that does not account for credit for applicable discounts.