Every appropriation answers three questions: what it can buy, how long you have to use it, and how much of it can cover what. Get those three right and the package lives. Get them wrong and it goes back, or worse, it becomes an Anti-Deficiency Act problem.
Plain-language walkthrough for program-office customers, plus picker and scenario tools that work as a quick reference for contracting officers. Covers O&M, RDT&E, Procurement, MilPers, and Working Capital Funds. MILCON gets a brief mention.
Congress appropriates money with strings attached. Three statutes in Title 31 carry most of those strings, and every funding question a CO asks traces back to one of them.
Every appropriation has a title in the law that tells you what Congress bought when they passed it. Operations & Maintenance is for operating and maintaining the force. Procurement is for buying end items. Research, Development, Test & Evaluation is for R&D. Military Construction is for construction. Mix them up and you have a purpose violation.
Under DoD financial policy, the working line between O&M and Procurement is the expense/investment threshold. As of now it sits at $350,000 per item or system. Below that, the item is an expense and O&M pays. Above that, it is an investment and Procurement pays.
An appropriation is available only to satisfy a need that arises during its period of availability. That is the Bona Fide Need Rule, and it is the single most audited concept in federal funding. If your FY26 O&M funds a widget you won't need until FY27, that is a BFN violation even if you signed the contract in September.
| Appropriation | Period of Availability | Typical uses |
|---|---|---|
| Military Personnel | 1 year | Pay and allowances, recruiting, PCS |
| Operations & Maintenance | 1 year | Day-to-day ops, training, maintenance, most services, expense items under $350K |
| RDT&E | 2 years | Research, development, prototypes, test and evaluation |
| Procurement | 3 years | Investment items over the expense/investment threshold, end items, major spares |
| Shipbuilding & Conversion, Navy | 5 years | Ships. Longer tail because they take years to build. |
| MILCON | 5 years | New construction, major renovations over the project threshold |
| Working Capital Fund | No-year | Depot maintenance, supply, transportation services. Revolving, not annual. |
When the period ends, the money does not vanish. It goes expired for five years, during which you can adjust existing obligations (make upward adjustments, liquidate accruals) but cannot create new ones. After those five years it goes closed, and any remaining balance is permanently gone from that year's appropriation.
Services that are severable (continuing, measurable by time) can cross fiscal years under a statutory exception. Under 10 USC 3133 (formerly 10 USC 2410a), a severable service contract may be funded with money available at the time of award for a period that begins in one fiscal year and ends in the next, up to a maximum of 12 months.
What this means in practice: if you sign a severable services contract on 1 July 2026 with FY26 O&M money, you can fund up to 30 June 2027. The BFN rule bends, but only for that specific 12-month window, and only for severable services.
The full-funding policy for procurement says each end item or useful increment must be fully funded in the year of procurement. You cannot buy half an airplane in FY26 and the other half in FY27. The whole thing is funded from one year's Procurement appropriation, usable across its 3-year window.
Incremental funding is the legal opposite, and it is allowed for a narrow set of things: RDT&E work that genuinely spans years, non-severable services over certain dollar thresholds when approved, and a few program-specific exceptions. DoD policy on incremental funding for services lives in DFARS 232.703-1 and DoDI 7000.14-R (the DoD FMR).
The Anti-Deficiency Act at 31 USC 1341 and 31 USC 1517 makes it unlawful to obligate or expend funds that have not been made available, or to obligate in excess of available funds. An ADA violation is not a paperwork issue. It is a statutory violation that requires formal investigation, a written report, and notice to Congress and the President.
Penalties include administrative discipline (reprimand, suspension, removal from federal service) and, for knowing and willful violations, criminal fines and up to two years imprisonment under 31 USC 1350. Plenty of them are referred for action every year across the services. Most involve someone cutting a corner or mis-mapping purpose or time.
The patterns that show up again and again across customer-handed-off packages:
Pick an appropriation to see what it covers, how long it's good for, and the common places program offices get it wrong.
Describe what you want to buy and the tool flags Purpose, Time, and Amount issues. Does not constitute legal or funding advice. Run it by your resource advisor and your CO.
Primary sources for the rules above.
Appropriations may only be applied to the objects for which the appropriations were made, except as otherwise provided by law.
Open 31 USC 1301 →The balance of a time-limited appropriation is available only for the payment of expenses properly incurred during the period of availability.
Open 31 USC 1502 →Prohibits obligations or expenditures in excess of available appropriations.
Open 31 USC 1341 →Prohibits obligations in excess of apportionments or allotments, and requires reporting of violations.
Open 31 USC 1517 →Permits a severable services contract period to begin in one FY and end in the next, up to 12 months.
Open 10 USC 3133 →Defines the expense and investment categories, the $350K threshold, and the exceptions.
Open DoD FMR Vol 2A →Used on severable services contracts that cross fiscal years.
Open FAR 52.232-19 →Principles of Federal Appropriations Law. The canonical reference on purpose, time, and amount.
Open GAO Red Book →