The U.S. defense budget breakdown for fiscal year 2026 starts with a single headline number: $838.7 billion in base discretionary funding for the Department of Defense, the largest slice of discretionary spending in the federal budget. That figure covers only the DoD. Add nuclear weapons work at the Department of Energy, defense-related activity at the FBI, and other national security functions across civilian agencies, and total spending under what Congress calls the 050 National Defense budget function climbs above $880 billion. To see where the money actually goes, you have to read the budget two ways: by what it buys, and by who spends it.
What the Money Buys
Congress funds defense through several broad appropriation accounts. Four of them dominate.
Operations and Maintenance
Operations and Maintenance, or O&M, is the biggest single category. The FY2026 enacted level is $294.4 billion.1U.S. House of Representatives. Defense Appropriations Act, 2026 Summary O&M pays for fuel, spare parts, vehicle and equipment repair, training exercises, base operations, and most of the military healthcare system delivered through facilities worldwide. It also covers the salaries of roughly 800,000 civilian DoD employees. Readiness lives in this account. When a unit can’t train or a ship sits in port waiting on maintenance, O&M is usually the account under pressure.
Military Personnel
Military Personnel, or MILPERS, received $193.3 billion in FY2026.1U.S. House of Representatives. Defense Appropriations Act, 2026 Summary This money covers basic pay, housing allowances, and food allowances for active-duty, reserve, and National Guard members. Pay scales are set by Title 37 of the United States Code and vary by rank and years of service.2Office of the Law Revision Counsel. 37 USC Chapter 7 – Allowances Other Than Travel and Transportation Allowances A new enlisted member at the E-1 grade earns about $2,407 per month in basic pay, or roughly $28,900 per year, before allowances. Senior officers with decades of service earn several times that. MILPERS also funds government contributions to Social Security and to Thrift Savings Plan retirement accounts for uniformed members.
Procurement
Procurement pays for new equipment coming off a production line: fighter jets, submarines, armored vehicles, satellites, ammunition. The FY2026 enacted level is $167.5 billion.1U.S. House of Representatives. Defense Appropriations Act, 2026 Summary These contracts run under the Defense Federal Acquisition Regulation Supplement, the uniform acquisition rulebook across the DoD.3Defense Acquisition Regulations System. Defense Federal Acquisition Regulation Supplement and Procedures, Guidance, and Information Major weapons programs often use multi-year contracts that lock in pricing across several fiscal years and generate savings compared to annual buys. Congress requires those deals to meet strict criteria, including a stable design, realistic cost estimates, and projected savings.
Research, Development, Test, and Evaluation
RDT&E funds the next generation of military technology. Congress enacted $145.9 billion for FY2026.1U.S. House of Representatives. Defense Appropriations Act, 2026 Summary The work runs from basic science in government labs through prototype testing to evaluation of finished systems before full production. Current priorities include artificial intelligence, hypersonic weapons, advanced cybersecurity, and next-generation space capabilities. Procurement buys what the military fights with today. RDT&E decides what it will fight with in ten or twenty years.
Military Construction
Military Construction, or MILCON, covers new and renovated bases, barracks, hospitals, training facilities, and family housing. The FY2026 request for construction and housing combined was $18.9 billion. A small slice compared to the others, but it shapes both quality of life for service members and the physical infrastructure everything else runs on.
Who Spends the Money
The four appropriation categories flow through four organizational channels: the three military departments and a centralized defense-wide pool. Each department manages its own mix of personnel, O&M, procurement, and RDT&E accounts.
Department of the Army
The Army’s FY2026 budget request totaled $197.4 billion. That money supports infantry, armored, and logistics units. The Army’s budget leans heavily toward personnel and operations, because ground warfare is labor-intensive. A large active-duty force, a substantial reserve component, and hundreds of installations at home and overseas drive much of the total.
Department of the Navy
The Department of the Navy runs a single budget covering both the Navy and the Marine Corps.4U.S. Government Accountability Office. Civilian Personnel – Additional Guidance and Consistent Data Reporting Could Help Improve the Marine Corps’ Budget Management Ship construction is the biggest cost driver. Aircraft carriers, submarines, and destroyers take years to build and cost billions per hull, which makes the Navy’s procurement account disproportionately large relative to its personnel numbers. Naval aviation adds another expensive layer, with carrier-based fighters and surveillance aircraft carrying their own procurement and sustainment pipelines.5Department of the Navy. Financial Management and Comptroller – Fiscal Year 2026
Department of the Air Force
The Department of the Air Force funds both the Air Force and the Space Force, the same way the Navy handles the Marine Corps.6United States Space Force. About the United States Space Force Its spending tilts toward high-value procurement and RDT&E, because aerospace platforms such as stealth bombers, tankers, and reconnaissance aircraft are extraordinarily expensive to develop and produce. The addition of the Space Force has brought growing financial responsibility for satellite constellations, missile warning systems, and orbital communications networks.
Defense-Wide Programs
Not every dollar flows through a military department. Defense-wide funding supports agencies and programs that serve the entire DoD. The Defense Health Program, budgeted at roughly $42.5 billion for FY2026, is the largest single component and delivers healthcare across the services.7Department of Defense. Defense Health Program Fiscal Year 2026 Budget Estimates The Defense Logistics Agency, which manages fuel, food, medical supplies, and spare parts across every branch, also draws from this pool.8U.S. Government Accountability Office. COVID-19: Defense-Wide Working Capital Fund Cash Management and Defense Logistics Agency Pandemic Response Centralizing these cross-service functions avoids the waste of each branch running duplicate logistics or healthcare systems.
Defense Dollars Outside the DoD
A significant share of national defense spending never touches the Department of Defense. The Department of Energy runs the nuclear weapons program through the National Nuclear Security Administration. The NNSA’s FY2026 request was $30 billion, covering maintenance and modernization of the warhead stockpile, dismantlement of retired weapons, and operation of national laboratories including Los Alamos and Sandia.9Department of Energy. DOE FY 2026 Volume 1 – NNSA The NNSA’s mission, set out in 50 U.S.C. § 2401, is to maintain the safety, reliability, and performance of the nuclear deterrent outside the operational control of the military.10Office of the Law Revision Counsel. 50 USC 2401 – Establishment and Mission
Other civilian agencies also receive defense-classified funding under the 050 function. More than half of the FBI’s budget falls into this category, financing counterterrorism and counterintelligence work. Portions of the Department of Homeland Security budget are counted there too. That is why the “national defense budget” and the “Department of Defense budget” are not the same number. The 050 total is always larger because it picks up defense-related work wherever it happens in the federal government.
Healthcare and Retirement: The Long-Tail Costs
Two obligations quietly consume a growing share of defense resources. The Military Health System provides care to 9.4 million beneficiaries, including active-duty members, retirees, and their families, through military hospitals and the TRICARE insurance network. Total MHS spending for FY2026 is projected at $64 billion once you add the Defense Health Program, personnel costs for military medical staff, facility construction, and accrual payments into the retiree healthcare fund.11Congress.gov. FY2026 Budget Request for the Military Health System
The Military Retirement Fund pays pensions to retired service members and carries its own long-term obligations. The DoD Actuary tracks the fund’s unfunded liability, the gap between promised future retirement payments and money already set aside. These healthcare and retirement costs don’t buy a single weapon or train a single unit, but they’re contractual obligations the government cannot easily reduce, and they compete directly with readiness and modernization funding.
How the Money Becomes Law
Every defense dollar moves through a two-step legislative process. The cycle begins when the President submits a budget request to Congress, typically in early February, for the fiscal year that starts October 1.12Congress.gov. Basic Federal Budgeting Terminology
Step one is authorization. The House and Senate Armed Services Committees draft the National Defense Authorization Act, which sets policies, establishes programs, and caps what can be spent on each activity.13House Armed Services Committee. History of the NDAA The NDAA tells the military what it is allowed to do and sets maximum dollar amounts. It does not release any money.
Step two is appropriation. The House and Senate Appropriations Committees draft the defense spending bill, which provides the legal authority to draw funds from the Treasury and sign contracts. Article I, Section 9 of the Constitution prohibits spending any money Congress has not specifically appropriated.14Congress.gov. ArtI.S9.C7.1 Overview of Appropriations Clause Both chambers must pass identical authorization and appropriations bills, and the President must sign them, before any defense funds can flow.
Unfunded Priorities Lists
The President’s budget request never includes everything the military wants. Federal law requires each service chief, combatant commander, and the Chief of the National Guard Bureau to submit an unfunded priorities list to Congress within 10 days of the budget release.15Office of the Law Revision Counsel. 10 USC 222a – Unfunded Priorities of the Armed Forces and Combatant Commands: Annual Report Those lists identify programs left out of the request, ranked by how much risk each omission creates. Congress uses them to add funding above the President’s number, and they often become leverage points in appropriations negotiations. The Secretary of Defense then consolidates all the individual lists into a single prioritized ranking.
What Happens Under a Continuing Resolution
The process above is how things are supposed to work. In practice, Congress rarely finishes on schedule. In 37 of the last 49 fiscal years, the DoD has started the year under a continuing resolution because Congress had not passed a full appropriations bill.16U.S. Government Accountability Office. Defense Budget: Effects of Continuing Resolutions on Selected Activities and Programs Critical to DOD’s National Security Mission
A CR keeps the government funded at roughly the prior year’s levels, but it comes with real constraints. The DoD cannot start new programs, increase production rates on weapons systems, or sign new contracts that weren’t funded the previous year. A GAO review found that about half of the acquisition programs surveyed reported schedule delays caused by CRs, including postponed contract awards and delayed equipment deliveries. When a CR drags past three months, obligation rates slow to a crawl early in the year and then spike later as programs rush to spend before the money expires. Training exercises get canceled, equipment shipments get postponed, and the administrative burden ripples through every contracting office in the department.
The Audit Problem
One caution goes with every number above. The Department of Defense is the only major federal agency that has never received a clean financial audit opinion. Full financial audits began in fiscal year 2018, and every year since, auditors have issued a “disclaimer of opinion,” meaning the DoD could not provide enough evidence to support the numbers in its financial statements.17U.S. Government Accountability Office. DOD Financial Management: Insights into the Auditability of DOD’s Fiscal Year 2024 Balance Sheet
For fiscal year 2024, the DoD’s Inspector General identified 28 department-wide material weaknesses in financial systems and internal controls. GAO analysis found those weaknesses directly affected $2.1 trillion in reported assets, roughly half of the DoD’s balance sheet, creating substantial risk that those figures are materially wrong. The underlying causes are systemic: outdated financial management systems, inconsistent data across components, and processes that were never designed with auditability in mind.
Congress set a deadline. The FY2024 NDAA requires the Secretary of Defense to achieve a clean audit opinion by December 31, 2028.18U.S. Government Accountability Office. DOD Financial Management: Status of Remediation Efforts To Meet Audit Mandate Some smaller components have earned clean opinions. The consolidated department-level statements remain far from passable. For a budget this size, the inability to verify where the money actually went is not just an accounting issue. It limits how confidently anyone, including Congress, can read the very breakdown described here.