appropriation. An Antideficiency Act violation can also occur when a contract uses funds in a period that falls outside of the time period the funds are authorized for use under what is known as the Bona Fide Needs rule (31 USC 1502), which provides: "The balance of a fixed-term appropriation is available only for payment of expenses properly incurred during the period of availability or to complete contracts properly made within that period." The Bona Fide Need Rule is a fundamental principle of appropriations law addressing the availability as to the time of an agency's appropriation. 73 Comp. Gen. 77, 79 (1994); 64 Comp. Gen. 410, 414-15 (1985). The rule establishes that an appropriation is available for obligation only to fulfill a genuine or bona fide need of the period of availability for which it was made. 73 Comp. Gen. 77, 79 (1994). It applies to all Federal Government activities carried out with appropriated funds, including contract, grant, and cooperative agreement transactions. 73 Comp. Gen. 77, 78-79 (1994). An agency's compliance with the bona fide need rule is measured at the time the agency incurs an obligation and depends on the purpose of the transaction and the nature of the obligation being entered into. 61 Comp. Gen. 184, 186 (1981) (bona fide need determination depends upon the facts and circumstances of the particular case). In the grant context, the obligation occurs at the time of the award. 31 Comp. Gen. 608 (1952). See also 31 U.S.C. Sec. 1501(a)(5)(B). Simply put, this rule states that the Executive Branch may only use current funds for current needs – they cannot buy items that benefit future year appropriation periods (i.e., 1 October through 30 September) without a specific exemption. The net result of this rule is funds expire after the end date for which Congress has specified their availability. For example, a single-year fund expires on 1 October of the year following their appropriation (i.e., FY07 appropriations. (for example, 1 October 2006 through 30 September 2007) expire on 1 October 2007). For example, operations and maintenance funds generally cannot be used to purchase supplies after 30 September of the year they are appropriated within with several exceptions – 1) the severable services exemption under 10 USC 2410 and Office of Management and Budget (OMB) Circular A-34, Instructions on Budget Execution, 2) Authorized stockage level exceptions and 3) long lead time exception. (see https://web.archive.org/web/20041027004108/https://www.safaq.hq.af.mil/contracting/affars/fiscal-law/bona-fide-need.doc