Social Security is self-funded. Nearly all of its money comes from three dedicated sources rather than general tax revenue: payroll taxes paid by workers and employers, interest earned on the program’s trust fund investments, and federal income taxes that some beneficiaries pay on the benefits they receive. Those revenues flow into legally separate trust funds that sit outside the regular federal budget, creating a closed loop between what workers pay in and what retirees, survivors, and people with disabilities draw out.
Payroll Taxes Do Most of the Work
The Federal Insurance Contributions Act (FICA) is the program’s main revenue engine. Employees pay 6.2 percent of their gross wages toward Social Security, and employers match that amount, for a combined 12.4 percent on every paycheck.1Social Security Administration. What is FICA? Participation is not optional for either side.
The 6.2 percent rate only applies up to an annual earnings cap that the Social Security Administration adjusts each year based on national average wage growth. For 2026, the cap is $184,500.2Social Security Administration. Contribution and Benefit Base A worker earning exactly that amount contributes $11,439, and the employer contributes the same. Wages above the cap are not subject to Social Security tax.
FICA also collects a separate 1.45 percent from each side for Medicare, with no earnings cap, plus an additional 0.9 percent on employee wages above $200,000.3Internal Revenue Service. Topic No. 751, Social Security and Medicare Withholding Rates Those Medicare dollars go to a different trust fund and do not support Social Security benefits.
If You Work for Yourself
Self-employed workers pay under the Self-Employment Contributions Act (SECA) rather than FICA. Without an employer to split the bill, you owe the full 12.4 percent Social Security tax on net self-employment earnings up to the same $184,500 cap.2Social Security Administration. Contribution and Benefit Base You can deduct the employer-equivalent half of your self-employment tax when calculating adjusted gross income, which lowers your income tax but not the self-employment tax itself.4Internal Revenue Service. Self-Employment Tax (Social Security and Medicare Taxes)
Whether the money comes through FICA or SECA, these mandatory contributions link your earnings to your future eligibility. That link is what makes Social Security a social insurance program funded by its participants rather than a welfare program funded from general revenue.
Where the Money Goes: The Trust Funds
Federal law establishes two separate accounts inside the U.S. Treasury: the Old-Age and Survivors Insurance (OASI) Trust Fund and the Disability Insurance (DI) Trust Fund.5Office of the Law Revision Counsel. 42 U.S. Code 401 – Trust Funds Every dollar of dedicated Social Security revenue flows into one of these two funds, and every benefit check and administrative cost comes back out of them.
The funds are classified as “off-budget,” meaning their operations are formally excluded from the unified federal budget.6Social Security Administration. Research Note 20 – The Social Security Trust Funds and the Federal Budget The designation is meant to keep the program’s finances visible as a separate line and to keep lawmakers from adjusting benefits just to balance the broader budget.
One nuance is worth understanding. Although the trust funds are legally separate, the surplus cash they collect does not sit in a vault. By law, any money not needed for immediate benefit payments must be invested in interest-bearing obligations issued or guaranteed by the United States.5Office of the Law Revision Counsel. 42 U.S. Code 401 – Trust Funds The federal government effectively borrows the surplus and spends it alongside other revenue, while the trust funds hold Treasury bonds as assets backed by the full faith and credit of the United States.6Social Security Administration. Research Note 20 – The Social Security Trust Funds and the Federal Budget
Interest on Trust Fund Investments
The trust funds hold “special-issue” Treasury securities, a type of bond that is not sold to the public and exists specifically for government trust funds.7Social Security Administration. Frequently Asked Questions About the Social Security Trust Funds The interest rate on these securities is tied to the average market yield on outstanding federal debt with at least four years remaining until maturity.5Office of the Law Revision Counsel. 42 U.S. Code 401 – Trust Funds
That interest is credited back to the OASI and DI funds. In 2024, the combined trust funds earned roughly $69.1 billion in investment income.8Social Security Administration. Financial Operations of the Trust Funds It is a meaningful secondary revenue stream on top of payroll taxes, generated without raising anyone’s tax rate.
Income Taxes on Benefits
The third revenue source is the federal income tax that some beneficiaries pay on the Social Security benefits they receive. Taxability depends on your “combined income,” calculated as your adjusted gross income plus any tax-exempt interest plus half of your Social Security benefits for the year.9Social Security Administration. Must I Pay Taxes on Social Security Benefits?
For a single filer, combined income between $25,000 and $34,000 makes up to 50 percent of benefits taxable, and combined income above $34,000 makes up to 85 percent taxable. For married couples filing jointly, the corresponding brackets are $32,000 to $44,000 for the 50 percent tier and above $44,000 for the 85 percent tier. These statutory thresholds have never been adjusted for inflation, so more beneficiaries cross them each year as wages and other income rise.10Office of the Law Revision Counsel. 26 U.S. Code 86 – Social Security and Tier 1 Railroad Retirement Benefits
The receipts do not stay in the general fund. The Treasury transfers them back to the OASI and DI trust funds, creating a feedback loop where taxes on today’s benefits help pay for tomorrow’s.9Social Security Administration. Must I Pay Taxes on Social Security Benefits? Eight states also impose their own income tax on Social Security benefits, with different exemptions and thresholds in each.
Self-Funded, But Facing a Shortfall
The self-funding model produced surpluses for decades, and the trust funds grew. That has changed. Starting in 2021, the OASI trust fund began paying out more in benefits than it collected from payroll taxes and benefit taxation combined, drawing down its reserves to cover the gap.
According to the 2025 Trustees Report, the OASI trust fund is projected to deplete its reserves by 2033. At that point, incoming payroll tax revenue would cover about 77 percent of scheduled retirement and survivor benefits.11Social Security Administration. Status of the Social Security and Medicare Programs The DI fund is in much stronger shape, projected to pay full benefits through at least 2099. Combining both funds, reserves are projected to run out in 2034, after which continuing income would cover about 81 percent of scheduled benefits.12Social Security Administration. 2025 OASDI Trustees Report
Depletion does not mean the program disappears. Payroll taxes would keep flowing in and would keep funding the majority of benefits. Without congressional action, though, beneficiaries would face an automatic reduction to whatever level current revenue can support. Proposals to close the gap include raising the taxable earnings cap, increasing the payroll tax rate, adjusting the retirement age, and modifying the benefit formula, alone or in combination. Congress closed a similar shortfall in 1983, and the longer any fix waits, the larger the required adjustment.