In this chapter, the following terms have the meanings indicated. Terms Defined. “Late payment” means any amount that is due and payable by law under a written procurement contract, without deferral, delay, or set-off under COMAR 21.02.07.03, and remains unpaid more than 37 days after an agency receives a proper invoice. “Payment” includes all required processing and authorization by the Comptroller of the Treasury, as provided under COMAR 21.02.07, and may be deferred, delayed, or set-off as applicable under COMAR 21.02.07.03. “Proper invoice” means a bill, written document, or electronic transmission, readable by the agency, provided by a vendor requesting an amount that is due and payable by law under a written procurement contract for property received or services rendered that meets the requirements of Regulation .02 of this chapter.