Glossary

Social Security trust fund

The accounts, holding special Treasury securities, that receive Social Security payroll taxes and pay benefits.

Also called: Social Security trust funds, OASDI trust fund

The Social Security trust funds are two accounts, one for retirement and survivors' benefits (OASI) and one for disability (DI), that receive payroll tax revenue and income from taxation of benefits and pay out benefits. Any surplus is invested in special-issue Treasury securities, which are claims on the government and are backed by its full faith and credit.

Since 2010 the program has paid out more than it takes in from taxes alone, and it has drawn on its trust fund reserves. The Social Security trustees project that the combined funds will be depleted in the 2030s, at which point incoming payroll taxes would cover only about four-fifths of scheduled benefits unless Congress acts. The exact year changes with each annual report.

There is debate about what the trust fund means. Some note that the securities are real legal obligations; others argue that they are an accounting device, since the government must raise money through taxes or borrowing to redeem them. Proposals to restore balance include raising the payroll tax or the wage cap, raising the retirement age, changing the benefit formula or using general revenue, and politicians disagree over which. Related programs are described as entitlements and part of mandatory spending.

Last reviewed November 8, 2026

In the index now

Related terms

Payroll tax A tax on wages that funds Social Security and Medicare, split between employers and employees. Entitlement A government benefit to which people are legally entitled if they meet eligibility rules, such as Social Security and Medicare. Unfunded liabilities Promised future benefits, such as Social Security and Medicare payments, that are not covered by dedicated funding projected to be available. Mandatory spending Federal spending set by permanent law rather than annual appropriations, including Social Security, Medicare and Medicaid. Means testing Limiting government benefits to people whose income or assets fall below a certain level.