OASDI Tax: What It Is and How It Differs from FICA

Picture your pay stub. Somewhere between "Gross Pay" and the number that actually lands in your bank account, there's a line labeled "OASDI" or "Social Security." Most people glance at it and move on. That line represents the single largest deduction many workers face, topping out at $11,439 per year in 2026. [1]

OASDI stands for Old-Age, Survivors, and Disability Insurance. It's the formal name for Social Security tax. And while it's technically just one piece of a larger payroll tax system, it's the piece with a cap, a funding debate, and a direct connection to the benefits check you'll receive (or already receive) in retirement.

30-Second Summary: OASDI is the Social Security payroll tax: 6.2% of wages up to $184,500 (2026), matched by your employer. Self-employed workers pay 12.4%. It funds retirement, survivor, and disability benefits. OASDI plus Medicare tax equals FICA. If "OASDI" appears on your pay stub, it's the same thing as "Social Security."

OASDI vs. FICA: What's the Difference?

OASDI is a subset of FICA, not a synonym.

When someone says "FICA tax," they mean both OASDI and Medicare together. When your pay stub says "OASDI," it means just the Social Security piece: 6.2%.

Your employer matches each component. So the government collects 12.4% for Social Security and 2.9% for Medicare on your wages, for a combined 15.3%. You see only half on your paycheck.

For the full picture of both components, rates, and worked examples, see our FICA tax guide.

The 2026 Wage Base: $184,500

Here's what makes OASDI different from Medicare: it has a ceiling.

In 2026, only the first $184,500 of your wages are subject to the 6.2% Social Security tax. [1] Income above that threshold? Not taxed for OASDI.

This cap rises most years. It was $176,100 in 2025 and $168,600 in 2024. The Social Security Administration adjusts it based on national average wage growth.

The practical effect is that the maximum any employee can pay in OASDI tax for 2026 is $11,439 (6.2% × $184,500). Their employer pays another $11,439. Self-employed workers pay up to $22,878.

Medicare, by contrast, has no cap and even charges an additional 0.9% surtax above certain income thresholds. [2] That's the key structural difference between the two FICA components.

How OASDI Tax Works: Employee vs. Self-Employed

Employees

If you're a W-2 employee, your employer withholds 6.2% of each paycheck for OASDI and remits it to the IRS. You have no control over this amount. There's no line on your W-4 to change it.

Example: Tomás, age 35, $72,000 salary

• OASDI: $72,000 × 6.2% = $4,464 per year
• Employer match: $4,464
• Total going to Social Security: $8,928

Tomás's monthly OASDI deduction is $372. He never touches that money, but it's recorded under his Social Security number and affects his future benefit calculation.

Self-Employed Workers

No employer to split the bill with. Self-employed individuals pay the full 12.4% through self-employment tax. [3]

Example: Maya, freelance graphic designer, $72,000 net earnings

• OASDI: $72,000 × 12.4% = $8,928
• Half-SE deduction for income tax: $4,464

Maya pays double Tomás's amount but deducts half when calculating her income tax. That deduction doesn't reduce the SE tax itself; it just lowers her taxable income for federal income tax purposes.

If Maya's net self-employment income were under $400, she wouldn't owe self-employment tax at all. That $400 threshold is surprisingly low and catches many gig workers off guard.

What OASDI Funds

Your OASDI contributions don't sit in a personal account with your name on it. They flow into the Social Security Trust Funds and pay benefits to today's recipients. Think of it less like a savings account and more like a generational conveyor belt: today's workers fund today's retirees, and tomorrow's workers will fund you.

The three types of benefits the program covers:

1. Old-Age (retirement): Monthly payments starting as early as age 62, with larger checks if you wait until 67 or 70. You need 40 credits (roughly 10 years of work) to qualify.
2. Survivors: If a worker dies, their spouse and children may receive monthly benefits based on the worker's earnings history.
3. Disability: Workers who become unable to work due to a qualifying medical condition can receive monthly benefits.

Your future benefit amount is calculated from your highest 35 years of earnings. Years with higher OASDI-taxed wages mean higher benefits. Years with zero earnings count as zeroes, which is why long career gaps can meaningfully reduce your Social Security check.

Who Is Exempt?

Almost nobody. But a few narrow categories exist:

• Certain religious groups (like the Amish) can file Form 4029 to opt out, but they waive all future Social Security benefits. [4]
• Some state and local government employees covered by qualifying pension plans established before 1984.
• Certain nonresident aliens on specific student or exchange-visitor visas.
• Students employed by their school, under specific conditions.

If you work two jobs and your combined wages exceed $184,500, both employers withhold independently. You may overpay OASDI. Claim the excess on your tax return for a credit or refund.

Why the Wage Cap Matters

The OASDI wage cap creates a regressive effect. Someone earning $90,000 pays 6.2% on every dollar. Someone earning $500,000 pays 6.2% on only 36.9% of their income. Their effective OASDI rate drops to about 2.3%.

This is a deliberate design choice. Benefits are also capped: your monthly Social Security check maxes out based on the same wage base. Higher earners don't pay more but also don't receive proportionally more.

Whether this cap should be raised or eliminated is one of the most debated questions in tax policy, particularly as the Social Security Trust Fund faces projected shortfalls. Reasonable people disagree sharply. But the math is clear: the cap means OASDI takes a bigger percentage from middle-income workers than from high earners.

Your Next Move

1. Check your pay stub. Look for the line labeled "OASDI" or "Social Security." Multiply your gross pay by 6.2% to verify the amount.
2. Create a my Social Security account at ssa.gov/myaccount to see your lifetime earnings record and estimated future benefits.
3. If you're self-employed, budget for the full 12.4% plus Medicare. Use estimated quarterly payments.
4. If you work two jobs, track combined wages against the $184,500 cap. Overpayments get credited on your return.
5. Understand how OASDI fits into your total tax load. It's one piece. Add Medicare, federal income tax, and state income tax to see the full picture. Use our tax bracket calculator to model it.

References

1. Social Security Administration. (n.d.). Contribution and Benefit Base. https://www.ssa.gov/oact/cola/cbb.html
2. IRS. (n.d.). Questions and Answers for the Additional Medicare Tax. https://www.irs.gov/businesses/small-businesses-self-employed/questions-and-answers-for-the-additional-medicare-tax
3. IRS. (n.d.). Self-Employment Tax. https://www.irs.gov/businesses/small-businesses-self-employed/self-employment-tax-social-security-and-medicare-taxes
4. IRS. (n.d.). Application for Exemption From Social Security and Medicare Taxes and Waiver of Benefits (Form 4029). https://www.irs.gov/pub/irs-pdf/f4029.pdf