No, OASDI is not the same as FICA. FICA is the federal payroll tax law that funds both Social Security and Medicare, and OASDI is only the Social Security half of it. When your pay stub lists an OASDI line and a Medicare line, together they make up your FICA withholding; when it lists a single “FICA” line, that one line already includes both.
What Each Acronym Stands For
FICA is the Federal Insurance Contributions Act, the law that authorizes payroll taxes on wages. It contains two separate taxes that fund two separate programs:
- OASDI, or Old-Age, Survivors, and Disability Insurance, is the formal name for Social Security. It pays retirement income, survivor benefits for families of deceased workers, and benefits for people with qualifying disabilities.
- HI, or Hospital Insurance, is the formal name for Medicare Part A, which covers inpatient hospital care.
So the relationship is straightforward: FICA is the container, OASDI and HI are what’s inside it. Any dollar withheld under FICA is either an OASDI dollar or an HI dollar.
The Rates and Who Pays Them
Your share of FICA is 7.65% of covered wages, and your employer pays a matching 7.65% from its own funds. That combined 15.3% breaks down like this:1Social Security Administration. Social Security and Medicare Tax Rates
- OASDI (Social Security): 6.2% from you, 6.2% from your employer, for a total of 12.4%.
- HI (Medicare): 1.45% from you, 1.45% from your employer, for a total of 2.9%.
The rate split is why the two pieces are usually listed separately on payroll systems. They fund different programs, they have different rules, and they behave differently once your wages climb.2Internal Revenue Service. Topic No. 751, Social Security and Medicare Withholding Rates
The Wage Cap Only Applies to OASDI
This is the biggest practical difference between the two halves of FICA, and it’s often the reason people start asking whether OASDI and FICA are the same thing in the first place.
OASDI has an annual wage cap. For 2026, the cap is $184,500. Once your year-to-date wages reach that number, your employer stops withholding OASDI for the rest of the calendar year, and withholding resets in January. At the 6.2% employee rate, the most anyone pays in OASDI tax for 2026 is $11,439.3Social Security Administration. Contribution and Benefit Base
HI has no cap. Every dollar you earn is subject to the 1.45% Medicare tax, no matter how high your wages go.2Internal Revenue Service. Topic No. 751, Social Security and Medicare Withholding Rates
If you hold more than one job at a time, each employer withholds OASDI on your wages independently, because neither knows what the other is paying you. Your combined OASDI withholding can therefore exceed the $11,439 maximum. When it does, you recover the overpayment as a credit on your federal income tax return.
How the Two Appear on Your Pay Stub and W-2
Pay stub labels vary by payroll system. You might see “OASDI,” “Social Security,” “SS,” “FICA-SS,” “FICA-Med,” or a single “FICA” line that combines both. If your stub shows one lump FICA figure, it already includes both Social Security and Medicare. If it shows two lines, one is OASDI and the other is Medicare.
Your W-2 is more consistent. Box 3 is your Social Security wages, capped at $184,500 for 2026. Box 4 is the Social Security tax withheld. Box 5 is your Medicare wages, with no cap. Box 6 is the Medicare tax withheld. Only your share appears on the W-2; your employer’s matching contribution is not shown there.4Internal Revenue Service. General Instructions for Forms W-2 and W-3 (2026)
If Box 5 is larger than Box 3, that’s normal. Someone earning $200,000 in 2026 would see $184,500 in Box 3 (Social Security wages hit the cap) and $200,000 in Box 5 (Medicare wages don’t).
The Additional Medicare Tax Is Not OASDI
High earners see an extra 0.9% withheld from wages once their pay crosses $200,000 in a calendar year. This is the Additional Medicare Tax, and although it rides alongside FICA on your paycheck, it is not part of OASDI and it is not matched by the employer. The 0.9% falls entirely on the employee.5Internal Revenue Service. Questions and Answers for the Additional Medicare Tax
The thresholds for owing the tax depend on filing status: $200,000 for single or head of household, $250,000 for married filing jointly, and $125,000 for married filing separately. Because employers use a flat $200,000 trigger regardless of how you file, the amount withheld may not match what you actually owe. You reconcile the difference on Form 8959.6Internal Revenue Service. Topic No. 560, Additional Medicare Tax
If You’re Self-Employed, It’s Called SECA
FICA applies to wages paid by an employer. If you work for yourself, you pay the equivalent tax under the Self-Employment Contributions Act, or SECA. The rate is the same 15.3% total, split into a 12.4% Social Security piece and a 2.9% Medicare piece, but you pay both halves yourself because there is no employer to match you.7Internal Revenue Service. Self-Employment Tax (Social Security and Medicare Taxes)
The IRS first reduces your net self-employment income to 92.35% before applying the 15.3%, which mirrors the fact that an employee doesn’t pay FICA on the employer’s share. You calculate the tax on Schedule SE and deduct half of it when figuring your adjusted gross income. The $184,500 Social Security wage base still limits the 12.4% piece, and the Additional Medicare Tax thresholds apply to net self-employment earnings as well.8Internal Revenue Service. Topic No. 554, Self-Employment Tax
The Short Version
OASDI is Social Security. FICA is Social Security plus Medicare. Whenever the two words sit next to each other on a paycheck, OASDI is one of the ingredients and FICA is the recipe.