The OASDI line on your paycheck is the federal payroll tax that funds Social Security. It takes 6.2% of your gross wages, your employer pays a matching 6.2%, and the money goes straight to the trust funds that pay retirement, survivor, and disability benefits. If you work in a covered job, the deduction is mandatory — you cannot opt out, and it is not the same thing as federal income tax.
The reason it shows up every pay period is that Social Security is pay-as-you-go. Current workers fund current beneficiaries, and in exchange your contributions build a work record that decides whether you qualify for benefits later and how much you receive.
What OASDI Stands For
OASDI is Old-Age, Survivors, and Disability Insurance. Those three words are three separate benefit programs, all paid for by the single tax on your stub:
- Old-Age: Monthly retirement income for workers who have earned enough credits and reached at least age 62. A spouse, even one who never worked, can collect up to half of the retired worker’s full benefit.
- Survivors: Payments to a deceased worker’s dependents, including a surviving spouse and unmarried children under 18 (or under 19 if still in high school).
- Disability Insurance: Income replacement for workers who can no longer work because of a qualifying medical condition, set at what the worker would have received at full retirement age.
Roughly 71 million Americans receive benefits from these programs, and the OASDI deduction on your paycheck is what pays them.
How the Amount Is Calculated
The math is simple: 6.2% of your gross wages, taken out of every paycheck until your year-to-date earnings hit the annual wage base limit. For 2026, that ceiling is $184,500. Once you cross it, OASDI withholding stops for the rest of the calendar year and restarts the following January.
Someone earning $80,000 pays 6.2% on every dollar, or $4,960 for the year, because their income never reaches the cap. A worker earning at or above $184,500 in 2026 pays the maximum of $11,439.00. The wage base rises most years to track the national average wage index — it was $168,600 in 2024 and $176,100 in 2025.
A few details catch people off guard. OASDI is calculated on gross pay, before income tax is subtracted. Section 125 cafeteria plan contributions, such as employer-sponsored health insurance premiums or a flexible spending account, do reduce your OASDI-taxable wages because those dollars are excluded before any tax is computed. Traditional 401(k) contributions do not — they lower your federal income tax but Social Security still counts them. And the employee share of OASDI is not deductible on your federal return.
The Employer Match and the Rest of FICA
The 6.2% on your stub is only half the contribution. Your employer pays another 6.2% that you never see, bringing the total to 12.4% of your wages up to the cap. Both halves go into the same trust funds.
OASDI is one piece of FICA, the Federal Insurance Contributions Act. The other piece is the Hospital Insurance tax, better known as Medicare, which is usually a separate line on your stub:
- OASDI (Social Security): 6.2% employee + 6.2% employer, applied up to $184,500 in 2026.
- Medicare: 1.45% employee + 1.45% employer, applied to every dollar of wages with no cap.
Together, your total FICA withholding is 7.65% of wages up to the OASDI cap, dropping to 1.45% on anything above it. Higher earners also pay an additional 0.9% Medicare surtax once wages pass $200,000 in a year, but that is a separate Medicare charge and does not affect the OASDI line.
If you are self-employed, you pay both halves yourself: 12.4% OASDI plus 2.9% Medicare, for a combined self-employment tax of 15.3% on net earnings up to the wage base. You can deduct half of the self-employment tax when calculating adjusted gross income, which W-2 employees cannot do.
What You Get for Paying It
Every dollar of OASDI tax you pay builds your work record with the Social Security Administration. You earn credits based on annual earnings. In 2026, each $1,890 in covered wages earns one credit, up to four credits per year, and the threshold adjusts annually with the wage index.
Most workers need 40 credits — roughly ten years of work — to qualify for retirement benefits. Disability benefits require fewer credits, and the exact number depends on your age when you become disabled. Credits never expire. Leave the workforce for a decade and come back, and your earlier credits are still on your record.
Work that does not pay OASDI does not earn credits, no matter how much you make.
Who Doesn’t Pay OASDI
Most workers have no option, but a few narrow categories are legally exempt.
Federal employees hired before January 1, 1984, who stayed in the Civil Service Retirement System do not pay OASDI on their federal earnings. Anyone hired on or after that date falls under the Federal Employees Retirement System and pays Social Security tax like a private-sector worker. State and local government coverage is a patchwork governed by Section 218 agreements between individual states and the Social Security Administration, and coverage attaches to the position, not the person.
Students enrolled and regularly attending classes at a college or university are exempt from OASDI on wages paid by that same school, which is why many campus jobs show no Social Security withholding.
Members of recognized religious groups that have existed continuously since December 31, 1950, and that conscientiously oppose all forms of public and private insurance can apply for an exemption using IRS Form 4029. Approval means no OASDI or Medicare tax, and a permanent waiver of all Social Security and Medicare benefits.
Foreign students and exchange visitors in F-1, J-1, or M-1 status who are still classified as nonresident aliens (generally their first five calendar years in the U.S.) are exempt from FICA on wages authorized by their visa. The exemption ends once they become resident aliens.
What If Too Much Was Withheld?
With a single employer, withholding stops automatically at the $184,500 cap. If you hold two or more jobs at the same time, each employer tracks the cap independently based only on what they pay you, so your combined OASDI withholding can exceed $11,439.00 for the year.
When that happens, claim the excess as a credit on your federal income tax return. The Form 1040 instructions cover the calculation under “Excess Social Security and tier 1 RRTA tax withheld.” Spouses filing jointly figure the excess separately. The IRS refunds the overpayment or applies it to any other tax you owe.
Where the Money Goes
OASDI revenue does not flow into the government’s general fund. It is deposited into two legally separate accounts at the U.S. Treasury:
- Old-Age and Survivors Insurance (OASI) Trust Fund: Pays retirement and survivor benefits.
- Disability Insurance (DI) Trust Fund: Pays disability benefits.
By law, these funds can only be used for benefit payments and program administration. Administrative costs have stayed at or below 1% of total spending since 1989, and in 2024 they were just 0.5%. Everything else goes to beneficiaries. When the funds take in more than they pay out, the surplus is invested in special-issue U.S. Treasury bonds that earn interest. When costs exceed revenue, the Administration redeems those bonds to cover the gap.
That is the full answer to what the deduction on your stub is doing: funding today’s Social Security benefits and earning you a claim on tomorrow’s.