The U.S. Treasury holds 28% of all federal budget authority but has committed the least of it among the four largest agencies — so through June 2026, Health and Human Services, not Treasury, leads the government in dollars obligated

USAspending.gov, the federal government's official award and account-balance portal mandated by the DATA Act, publishes for every top-tier agency two different measures of the same money: budget authority (the legal permission to obligate funds) and obligations (the dollars an agency has actually committed to contracts, grants, benefits and payroll). We pulled the free `references/toptier_agencies` endpoint this run (retrieved 2026-08-11; the data reflect fiscal year 2026 through the third quarter, i.e. October 1, 2025–June 30, 2026), which returns all 111 top-tier agencies with their fiscal-year-to-date budget authority, obligations and outlays. USAspending states a government-wide total budget authority of $16,047.1 billion; the 111 listed agencies sum to $15,908.0 billion of it, a $139.0 billion (0.87%) residual. Reported obligations across the 111 agencies total $8,225.8 billion and outlays $7,894.4 billion. Measured against the stated government-wide total, agencies have obligated 51.3% of budget authority with three quarters of the fiscal year elapsed; against the summed agency authority, 51.7%. Ranked by **budget authority**, the four largest agencies are the Department of the Treasury ($4,514.3 billion, 28.13% of the government-wide total), Health and Human Services ($3,436.2 billion, 21.41%), Defense ($2,575.2 billion, 16.05%) and the Social Security Administration ($1,421.6 billion, 8.86%). The top two hold 49.5% of all federal budget authority between them, the top three 65.6%, the top six 81.7%. Ranked by **obligations** — dollars actually committed — the same four agencies still lead, but the order changes: HHS is first ($2,220.8 billion, 27.00% of all obligations), Treasury second ($1,697.2 billion, 20.63%), SSA third ($1,359.6 billion, 16.53%) and Defense fourth ($1,285.0 billion, 15.62%). Two adjacent pairs swap: Treasury and HHS trade the top two spots, and Defense and SSA trade the next two. The top three by obligations hold 64.2% of the total, the top four 79.8%. The reordering is a direct function of each agency's **execution rate** — obligations divided by budget authority. Treasury has obligated 37.6% of its authority; HHS 64.6%; Defense 49.9%; SSA 95.6%. Because HHS is committing nearly two-thirds of its smaller authority while Treasury commits barely over a third of its larger one, HHS overtakes Treasury in dollars obligated even though Treasury outranks it in authority by $1,078.1 billion. The same arithmetic lifts SSA (95.6%) above Defense (49.9%). Across all 36 agencies holding more than $1 billion in budget authority, the execution rate ranges from 2.6% at the Farm Credit System Insurance Corporation to 95.6% at SSA. The lowest rates cluster among insurance and guarantee funds — Farm Credit (2.6%), the Federal Deposit Insurance Corporation (2.9%, on $146.1 billion of authority), the Pension Benefit Guaranty Corporation (10.1%) — while the highest belong to benefit-paying agencies: SSA (95.6%), the Railroad Retirement Board (72.4%) and the Small Business Administration (72.5%). Housing and Urban Development, ninth in authority at $338.8 billion, sits near the low end at 21.1% and drops out of the top ten by obligations entirely.

The following is analysis, not fact. Budget authority and obligations are not two names for the same number; they are two stages of one process, and a table sorted by the first tells a different story than the same table sorted by the second. Authority is a snapshot of the government's spending permission — where the balance sheet's capacity sits. Obligations are a record of decisions already made — where money has actually been put to work. This piece's single finding is that ranking the identical 111-agency ledger by those two columns reorders the leaders, and that the reorder is not noise: it is execution rate, made visible. The mechanism is arithmetic. An agency's obligation share equals its authority share times its execution rate, normalized. Treasury's 28.1% of authority multiplied by a 37.6% execution rate lands it below HHS, whose 21.4% of authority multiplied by 64.6% carries further. Nothing about the two agencies' relative size explains the flip; only the fraction of authority each has chosen or been able to commit does. The same lever moves SSA — which at a 95.6% execution rate obligates almost every dollar it holds — above a Defense department that has committed under half of its far larger authority. What the whole ledger shows that any single row conceals is the width of the execution spread: from 2.6% to 95.6% among the 36 largest holders. That range is the real subject. It means the four agencies that dominate the government's authority are not the four that dominate its committed spending in the same order, and it means that reading budget authority as a proxy for "how much an agency is spending" — a common shorthand — mis-ranks the government three quarters of the way through its year. USAspending records the two numbers; it does not editorialize on why they diverge, and neither does this piece. It reports the divergence and the arithmetic that produces it.

The sharpest caution is against reading execution rate as diligence, thrift or waste. It is none of those. Budget authority mixes one-year, multi-year, no-year, revolving and trust-fund money, and much of it is never meant to be obligated inside a single fiscal year. SSA's 95.6% is high because Social Security benefits are mandatory obligations that flow out on a fixed schedule; FDIC's 2.9% and Farm Credit's 2.6% are low because deposit- and loan-insurance funds are authority held in reserve against contingencies, by design largely unobligated; PBGC's 10.1% and HUD's 21.1% reflect guarantee reserves and multi-year grant and contract authority that obligates slowly and lawfully. A low execution rate is not underspending, and a high one is not efficiency. The number measures the ratio of two reported figures and nothing beyond it. Second, the timing frame. This is a Q3 snapshot — through June 30, 2026, roughly 75% of the fiscal year by calendar. But "current" fiscal-year-to-date budget authority grows through the year as appropriations, supplementals and transfers are enacted, so the 51.3% government-wide obligation share is measured against authority-recorded-to-date, not against a final full-year figure. It does not imply the government is "behind." Obligations also concentrate in the fourth quarter for many discretionary accounts. Third, reconciliation. USAspending's stated government-wide total ($16,047.1 billion) exceeds the sum of the 111 listed agencies ($15,908.0 billion) by $139.0 billion (0.87%); shares here are computed against the stated total to match USAspending's own percentage field, so the listed agencies' authority shares sum to about 99.1%, not 100%. The figures are agency-reported under the DATA Act and are revised in later submissions; a re-pull weeks from now may move the decimals. The robust claims are the large, structural ones — the top-four reordering, the 37.6%-vs-64.6% Treasury/HHS gap, the 2.6%-to-95.6% execution spread — not the third digit of any single rate.

From the vantage of a budget-authority table — the view that leads most "biggest agencies" rankings — the federal government's order is settled: Treasury, then HHS, then Defense, then Social Security. That ranking is accurate, and it is the one most often quoted, because authority is the number appropriations produce and the number headlines reach for. It also answers a different question than most readers think it does. Authority is permission; it is not spending. Sort the identical ledger by what has actually been committed and Treasury falls behind HHS, Defense falls behind Social Security, and a housing department that ranks ninth in authority disappears from the top ten entirely. The two tables are built from the same rows. They disagree because one records what agencies may spend and the other records what they have — and the gap between those two columns, agency by agency, is the whole story.

A desk covering federal spending reaches for the budget-authority table and reports the order it finds: Treasury biggest, then HHS, then Defense, then Social Security. The order is right, and it quietly answers the wrong question — it ranks permission to spend, not spending. Pull the same 111-agency ledger and read its second column, obligations, and the top four reorder: HHS passes Treasury, SSA passes Defense, because Treasury has committed only 37.6% of its authority while HHS has committed 64.6% and SSA 95.6%. The reordering isn't a quirk of two agencies; it's the visible edge of an execution spread that runs from 2.6% to 95.6% across the 36 largest holders — insurance and guarantee funds sitting almost untouched by design at the bottom, benefit-paying agencies near the top. No single row shows it. Only sorting the whole table twice, and dividing one column by the other, reveals that the government's authority ranking and its spending ranking are not the same list.