| Actuarial deficit |
The average amount, over the 75-year projection period, by which a trust fund's cost exceeds its income, expressed as a percentage of taxable payroll (Sections 6 and 7). |
| Antideficiency Act |
The laws (31 U.S.C. 1341, 1342, 1349-1351, 1517-1519) that bar obligating or spending more than an appropriation or apportionment allows (Section 1). |
| Apportionment |
The legally binding plan, approved by OMB on form SF 132, that divides an appropriation by time period or activity (Section 1). |
| Appropriation (budget authority) |
Authority in law for an agency to make obligations and pay them. |
| Appropriated entitlement |
A mandatory payment that the law requires but that is funded through an annual appropriations act, such as Medicaid, SSI and SNAP (Section 4). |
| Authorization |
A law that creates or continues a program; an "authorization of appropriations" states an amount that may be appropriated but provides no money (Section 1). |
| Calendar year (CY) / fiscal year (FY) |
The Trustees Reports use calendar years; federal budget and Treasury figures use fiscal years, October 1 to September 30. FY2026 runs Oct. 1, 2025 to Sept. 30, 2026. |
| Clawback (Part D state payments) |
Payments states make to Medicare Part D because Medicare took over prescription-drug costs Medicaid used to pay for people enrolled in both programs (Section 5). |
| DEFC |
Disaster Emergency Fund Code: a tag linking spending to the emergency or supplemental law that provided it (Section 3). |
| Depletion (of a trust fund) |
The point at which a trust fund's reserves are used up; afterwards it can pay only what its income covers. Often called "insolvency" (Sections 6 and 7). |
| DI |
The Federal Disability Insurance Trust Fund (Social Security disability benefits). |
| Expired / closed account |
A fixed-period account after its period of availability ends (expired: five years, old obligations only) and after it is closed and its balance canceled (Section 2). |
| Federal account |
On USAspending, the agency identifier plus main account code, grouping all the Treasury Account Symbols of one account (Section 2). |
| General revenue (general fund) |
Federal money not earmarked for a trust fund: mainly individual and corporate income taxes, and borrowing. |
| GTAS |
Governmentwide Treasury Account Symbol Adjusted Trial-Balance System, through which agencies report budget execution data, including the SF 133, to the Treasury (Section 3). |
| HI |
The Federal Hospital Insurance Trust Fund (Medicare Part A). |
| Hold harmless |
The rule limiting a Social Security recipient's dollar increase in the Part B premium to the dollar increase in their benefit (Section 5). |
| Impoundment Control Act |
The 1974 law (2 U.S.C. 681 and following) governing presidential proposals to cancel (rescind) or delay (defer) appropriated money (Section 1). |
| IRMAA |
Income-related monthly adjustment amount: the higher Part B and Part D premiums paid by higher-income enrollees (Section 5). |
| Mandatory spending |
Spending set by permanent laws on eligibility and benefits rather than by annual appropriations (Section 4). |
| Medicare funding warning |
The warning the Medicare Trustees issue when, in two consecutive reports, the part of Medicare spending not covered by dedicated financing is projected to exceed 45 percent within seven years (Section 5). |
| No-year / multi-year / annual money |
Budget authority available until spent ("until expended"), for a stated period longer than a year, or for one fiscal year (Section 2). |
| OASI / OASDI |
The Federal Old-Age and Survivors Insurance Trust Fund (Social Security retirement and survivor benefits); OASDI is OASI and DI shown together (Section 7). |
| Obligation / outlay |
A legally binding commitment to pay (a contract, grant or salary) / the payment itself. |
| PAYGO (statutory) |
The Statutory Pay-As-You-Go Act of 2010, which records the budget effect of new laws on mandatory spending and revenue and can trigger a sequester (Section 4). |
| SF 133 |
Report on Budget Execution and Budgetary Resources, filed for every expired and unexpired account (Section 3). |
| SMI |
The Federal Supplementary Medical Insurance Trust Fund, with separate accounts for Medicare Part B and Part D (Section 5). |
| TAS |
Treasury Account Symbol: the identifier of an account for one period of availability (Section 2). |
| Taxable maximum |
The annual wage limit up to which the Social Security payroll tax applies: $184,500 in 2026 (Section 7). The Medicare payroll tax has no limit. |
| Unfunded obligation |
The present value of a trust fund's projected cost in excess of its income and reserves over the projection period (Sections 6 and 7). |