overpayment

“overpayment” means any payment by a lessee or its designee in excess of an amount legally required to be paid on an obligation and includes the portion of any estimated payment for a production month that is in excess of the royalties due for that month;

The term “overpayment” means any funds that a person receives or retains under subchapter XVIII or XIX to which the person, after applicable reconciliation, is not entitled under such subchapter.