OASDI is the Social Security and Medicare tax taken from your wages

OASDI stands for Old-Age, Survivors, and Disability Insurance. It is the Social Security tax line item on your paycheck stub. When you see "Social Security" or "FICA" listed as a deduction, that includes OASDI.

The OASDI tax funds two programs: Social Security retirement benefits and Social Security Disability Insurance (SSDI). Your employer withholds 6.2% of your gross wages up to a yearly earnings cap. If you are self-employed, you pay both the employee and employer portions, which totals 12.4%.

The earnings cap changes each year based on wage growth. In 2024, you pay OASDI tax on earnings up to $168,600. Once your wages exceed that amount in a calendar year, no more OASDI tax is withheld from your remaining paychecks that year.

Key Takeaways

  • OASDI tax is 6.2% of your wages if you are an employee, withheld by your employer, and funds Social Security retirement and disability benefits.
  • The tax applies only to earnings below an annual cap, which was $168,600 in 2024 and increases yearly.
  • Once you reach the earnings cap in a calendar year, no additional OASDI tax is taken from your paychecks for the rest of that year.
  • Self-employed workers pay 12.4% total OASDI tax (both employee and employer shares) on net business income up to the same annual cap.
  • OASDI is separate from Medicare tax (1.45%), though both appear on your paycheck and together make up FICA withholding.

How much OASDI tax comes out of each paycheck

The amount depends on your gross wages and how many paychecks you have received so far that year. If you earn $4,000 per paycheck and have not yet hit the earnings cap, you pay $248 in OASDI tax that pay period (6.2% of $4,000).

Your employer calculates this withholding on each paycheck independently. If you change jobs mid-year, your new employer starts fresh and withholds OASDI tax until you reach the cap again. If you worked for two employers and together earned above the cap, you may have overpaid OASDI tax. You can claim a credit for the overpayment when you file your tax return.

The earnings cap is the only limit on OASDI withholding. There is no cap on Medicare tax (1.45%), which is why high earners see Medicare tax continue on their paychecks all year while OASDI tax stops.

Why OASDI tax is withheld from your paycheck

OASDI tax funds the Social Security Trust Fund, which pays benefits to retirees, disabled workers, and survivors of deceased workers. When you pay OASDI tax, you are building a record of earnings that determines your future Social Security benefits.

Social Security tracks your earnings history under your Social Security number. The more you earn and pay OASDI tax over your working years, the higher your retirement benefit will be when you reach full retirement age. Disability and survivor benefits also depend partly on your OASDI tax contributions.

You must have earned income and paid OASDI tax to be covered by Social Security. Certain government employees who do not pay OASDI tax may not be covered by Social Security, though they may participate in an alternative pension system.

OASDI tax versus Medicare tax on your paycheck

OASDI and Medicare are two separate taxes that together make up FICA (Federal Insurance Contributions Act) withholding. OASDI is 6.2% and funds Social Security. Medicare tax is 1.45% and funds the Medicare health insurance program.

The key difference is the earnings cap. OASDI tax stops once you reach the annual cap, but Medicare tax has no cap and continues on all wages throughout the year. High earners also pay an additional 0.9% Medicare tax on wages above $200,000 (single) or $250,000 (married filing jointly).

Both taxes appear separately on your paycheck stub so you can see exactly how much goes to each program. Your employer matches both amounts, though you only see your employee share deducted from your pay.

What happens when you reach the OASDI earnings cap

Once your cumulative wages for the year reach the cap, your employer stops withholding OASDI tax. If you are paid biweekly and earn $6,500 per paycheck, you will hit the cap partway through the year and then see no OASDI deduction on later paychecks.

This means your take-home pay increases slightly in the paychecks after you reach the cap, because OASDI tax is no longer withheld. Medicare tax continues as usual.

If you work for multiple employers in the same year, each employer withholds OASDI tax independently until you reach the cap. You may end up paying more OASDI tax than required if your combined earnings from all jobs exceed the cap. The IRS allows you to claim a credit for excess OASDI tax paid when you file your annual tax return.

Self-employed workers and OASDI tax

If you are self-employed, you pay both the employee and employer shares of OASDI tax, totaling 12.4% of your net business income. You calculate this as part of your self-employment tax when you file your annual tax return using Schedule SE.

The same earnings cap applies. You pay self-employment tax on net business income up to $168,600 (in 2024) and no more. Like employees, you can deduct half of your self-employment tax as an adjustment to income on your tax return.

Self-employed workers do not have an employer to withhold taxes, so you may need to make quarterly estimated tax payments to cover your OASDI, Medicare, and income tax liability.

How OASDI tax affects your Social Security benefits

Your Social Security retirement benefit is calculated using your 35 highest-earning years. The more you earn and pay OASDI tax, the higher your benefit will be. Years with no earnings or low earnings count as zeros in the calculation, which lowers your average.

You must have earned at least 40 credits (roughly 10 years of work with OASDI tax contributions) to be covered by Social Security retirement benefits. Disability and survivor benefits require fewer credits depending on your age when you become disabled or die.

The Social Security Administration maintains a record of your earnings and OASDI tax contributions. You can view your earnings record online through your my Social Security account to verify it is accurate.

Frequently Asked Questions

Why does OASDI tax stop partway through the year for high earners?

The OASDI earnings cap limits how much income is subject to Social Security tax. This cap exists because Social Security benefits are designed to replace a portion of average earnings, not to tax unlimited income. Once you reach the cap, no additional OASDI tax is withheld for the rest of that calendar year.

Can I get a refund if I paid too much OASDI tax?

If you worked for multiple employers and your combined earnings exceeded the cap, you overpaid OASDI tax. You cannot get a refund directly, but you can claim a credit for the excess when you file your annual tax return. The IRS will reduce your tax liability by the amount you overpaid.

What if I did not pay OASDI tax because I was exempt?

Some workers, such as certain government employees, are exempt from OASDI tax and do not build Social Security credits. If you were exempt, you may not be covered by Social Security retirement or disability benefits. Check with your employer or the Social Security Administration if you are unsure about your coverage status.

Does OASDI tax count toward my income tax?

No. OASDI tax is a separate payroll tax from federal income tax withholding. Both are deducted from your paycheck, but they fund different programs and are calculated differently. Your OASDI tax does not reduce your taxable income for federal income tax purposes.

What is the difference between OASDI and FICA?

FICA is the umbrella term for all Social Security and Medicare payroll taxes. OASDI is the Social Security portion of FICA (6.2%), and Medicare tax is the other portion (1.45%). Together they make up your total FICA withholding.