Federal spending divides into two main categories: mandatory outlays, which flow automatically under permanent law, and discretionary outlays, which Congress must approve each year through appropriations. The split is lopsided. Of the $7.4 trillion the Congressional Budget Office projects the Treasury will pay out in fiscal year 2026, mandatory programs account for roughly three-quarters and discretionary spending for about one-quarter, with net interest on the debt sitting outside both.1Congressional Budget Office. The Budget and Economic Outlook: 2026 to 2036 Understanding the difference between mandatory and discretionary federal outlays is the key to reading almost any budget headline, because the two categories operate under entirely different rules and respond to entirely different pressures.
What Counts as an Outlay
An outlay is the moment cash actually leaves the Treasury to settle a federal obligation. It is distinct from budget authority, which is the legal permission Congress gives an agency to commit money in the first place.2Congressional Research Service. Basic Federal Budgeting Terminology Congress can authorize a large project one year, but the outlays for that project may spread over several years as invoices come in. When people talk about federal spending totals, they usually mean outlays, because that is the number that hits the deficit.
Every outlay traces back to an appropriation. The Antideficiency Act bars federal employees from spending or committing funds beyond what Congress has made available, or from obligating the government before an appropriation exists.3Office of the Law Revision Counsel. 31 USC 1341 – Limitations on Expending and Obligating Amounts What varies between mandatory and discretionary programs is not whether an appropriation is required, but how and when Congress provides it.
Mandatory Outlays
Mandatory spending runs on autopilot. The programs are written into permanent law, so the Treasury must pay anyone who meets the eligibility criteria without waiting for Congress to vote each year. Total mandatory outlays in any given year depend on how many people qualify and what benefit formulas dictate, not on the annual budget debate.
Social Security
Social Security is the single largest line item in the federal budget. Benefits are calculated using a formula based on up to 35 years of a worker’s indexed earnings, producing a primary insurance amount that becomes the baseline monthly payment.4Social Security Administration. Social Security Benefit Amounts Because outlays depend on how many people are collecting and what each person’s formula produces, total spending rises automatically as the population ages.
Payments also adjust for inflation each year. For 2026, the Social Security Administration announced a 2.8 percent cost-of-living adjustment, calculated from changes in the Consumer Price Index for Urban Wage Earners and Clerical Workers.5Social Security Administration. Social Security Announces 2.8 Percent Benefit Increase for 2026 The COLA pushes aggregate outlays higher even if the number of beneficiaries stays flat, and when prices rise quickly, the effect compounds for years.
Medicare and Medicaid
Medicare provides health insurance primarily for people aged 65 and older, covering hospital stays, outpatient care, and prescription drugs.6Medicare. Get Started With Medicare Medicaid serves lower-income individuals and families. Both are entitlements: the government is legally bound to cover eligible beneficiaries regardless of what the spending total turns out to be. The faster health care costs rise or the more people enroll, the more money flows out of the Treasury.
Other Mandatory Programs
Smaller mandatory categories include veterans’ benefits, federal employee retirement, and nutrition assistance. The Supplemental Nutrition Assistance Program, for example, is authorized by the Food and Nutrition Act, and its benefits are classified as obligations of the United States.7eCFR. 7 CFR Part 271 – General Information and Definitions These programs act as automatic stabilizers. When the economy weakens and more people qualify, outlays increase without a congressional vote. When conditions improve, spending contracts on its own.
Discretionary Outlays
Discretionary spending is the portion of the budget Congress must actively renew each year through appropriation bills. CBO projects about $1.9 trillion in discretionary outlays for fiscal year 2026.1Congressional Budget Office. The Budget and Economic Outlook: 2026 to 2036 The category splits into defense and non-defense, and the balance between them is one of the most visible annual policy fights in Washington.
Defense
The Department of Defense receives the largest share of discretionary funding, covering military pay, weapons procurement, research, and ongoing operations. Unlike mandatory programs, defense outlays can swing significantly from year to year depending on operational tempo or shifts in strategic posture. Congress controls the dial through the annual National Defense Authorization Act and the corresponding defense appropriation.
Non-Defense
Everything else in the discretionary bucket falls under non-defense: education grants, transportation infrastructure, environmental regulation, scientific research, law enforcement, and diplomatic operations. Agencies like the Department of Education, the Department of Transportation, and the Environmental Protection Agency depend on these annual appropriations. If Congress cuts an agency’s funding, that agency’s outlays drop the following year in a way mandatory programs simply do not.
The Annual Cycle and Continuing Resolutions
The cycle begins when the President submits a budget request to Congress, as required by federal law, between the first Monday in January and the first Monday in February.8Office of the Law Revision Counsel. 31 USC 1105 – Budget Contents and Submission to Congress Congress then works on twelve separate appropriation bills, though in practice these are frequently bundled. If none of this is finished by October 1, when the fiscal year starts, Congress passes a continuing resolution to keep agencies funded temporarily at roughly the prior year’s levels.9U.S. GAO. What is a Continuing Resolution and How Does It Impact Government Operations?
Continuing resolutions are not harmless placeholders. Agencies operating under one face real constraints: hiring slows or stops, travel budgets may be frozen, and grant announcements carry disclaimers that final funding depends on congressional action. New programs cannot launch, and existing programs cannot expand. If Congress fails to pass even a continuing resolution, a shutdown begins and discretionary outlays for non-essential functions stop entirely. Mandatory outlays keep flowing during a shutdown because their authority does not depend on the annual bills.
Where Net Interest Fits
Net interest on the public debt is neither mandatory nor discretionary in the usual sense, but it now rivals both. CBO projects net interest outlays of roughly $1.0 trillion in fiscal year 2026, consuming about 19 percent of all federal revenue.10House Budget Committee. CBO Baseline February 2026 Interest payments exceeded defense spending for the first time in nearly a century in 2024 and are projected to stay above defense every year going forward.
The total interest bill depends on how much debt is outstanding and what rates the government locked in when it borrowed. The “net” figure subtracts interest the government pays to its own trust funds, leaving only the cash flowing to outside creditors. These outlays are unavoidable as long as the debt exists.
Why the Split Matters Going Forward
Two of the largest mandatory programs face funding shortfalls that will change the outlay picture within the next decade. The Social Security Old-Age and Survivors Insurance trust fund is projected to be depleted by 2033, at which point incoming payroll tax revenue would cover only about 77 percent of scheduled benefits.11Social Security Administration. A Summary of the 2025 Annual Reports The Medicare Hospital Insurance trust fund faces the same depletion year.12Centers for Medicare & Medicaid Services. 2025 Medicare Trustees Report
Depletion does not mean the programs disappear. Payroll taxes keep flowing in, so reduced benefits could still be paid. But without legislative changes, the law would require automatic cuts or some other adjustment, and long-term projections for mandatory outlays diverge sharply based on what Congress eventually does.
Where to See the Numbers Yourself
Day-to-day visibility comes from the Treasury. The Daily Treasury Statement reports the government’s cash position, including deposits, withdrawals, and public debt transactions, updated each business day.13U.S. Treasury Fiscal Data. Daily Treasury Statement (DTS) The Monthly Treasury Statement provides a broader summary of receipts, outlays, and the running surplus or deficit, and is the standard resource for checking whether actual spending is running ahead of or behind projections.14Bureau of the Fiscal Service. Monthly Treasury Statement Both track the fiscal year, which runs from October 1 through September 30.15USAGov. The Federal Budget Process
For award-level detail, USAspending.gov is the official open data source for federal spending, covering contracts, grants, loans, and other awards.16USAspending. Government Spending Open Data Between these tools, essentially every dollar the government pays out is documented in a publicly accessible format, and you can trace any given outlay back to the mandatory or discretionary authority behind it.