This is the deduction on a payslip that funds retirement, survivor and disability benefits, and for most employees it is simply a line they never examine.
It becomes worth understanding at two moments: when somebody works more than one job in a year, and when somebody moves from employment to working for themselves and discovers both halves now fall on them.
This covers what the charge is, how it sits alongside the other employment taxes, how it appears on a payslip, how it works for the self-employed, the exemptions that exist, and what happens when too much has been paid.
What Is OASDI Tax?
OASDI stands for Old Age, Survivors, and Disability Insurance. It is the formal name for Social Security tax, the federal payroll tax that funds Social Security retirement, survivor, and disability benefits. Every employee and employer in the United States pays OASDI tax on covered wages.
Moving from employment to self-employment is where this lands hardest, because both halves now fall on the same person and it arrives through the return rather than quietly off a payslip. It is the most common budgeting shock of a first self-employed year.
Anu Gupta, CA, EA, B.Tech · LinkedInOASDI Tax Rates
| Who Pays | Rate |
|---|---|
| Employee | 6.2% |
| Employer | 6.2% |
| Total (combined) | 12.4% |
| Self-employed (all in) | 12.4% on net SE income |
Wages above the annual wage base are not subject to OASDI tax. There is no wage base cap for Medicare tax.
OASDI Alongside Medicare Tax (FICA)
Together, OASDI and Medicare taxes form FICA (Federal Insurance Contributions Act) tax. Here is how the rates stack:
| Tax Component | Employee Rate |
|---|---|
| OASDI (Social Security) | 6.2% |
| Medicare (standard) | 1.45% |
| Total FICA, employee | 7.65% |
| Total FICA, employer match | 7.65% |
| Additional Medicare Tax (>$200k single / $250k MFJ) | 0.9% employee only |
Self-employed individuals pay the full 15.3% (12.4% OASDI + 2.9% Medicare) on net self-employment income, but they can deduct half of SE tax as an above-the-line deduction on Schedule 1.
How OASDI Appears on Your Pay Stub
Look for any of these labels on your pay stub:
- OASDI
- Social Security Tax
- SS Tax
- FICA-SS
- Fed OASDI/EE (employee portion)
The employer match of 6.2% never appears on your pay stub, it is paid directly by your employer to the IRS and is an additional cost of employment.
Self-Employed: Calculating and Deducting OASDI
If you are self-employed (sole proprietor, single-member LLC, partner), you file Schedule SE to calculate SE tax.
- Multiply net profit from Schedule C by 92.35% (the SE income factor) to get net earnings subject to SE tax.
- Apply 15.3% to the first $176,100 and 2.9% above that.
- Deduct 50% of total SE tax on Schedule 1, Line 15, this reduces your income tax (not SE tax itself).
Pro Tip: S-corporation owners can reduce OASDI exposure by paying themselves a reasonable salary and taking additional profit as distributions, distributions are not subject to FICA or SE tax.
OASDI Exemptions
Most workers pay OASDI, but there are limited exemptions:
| Exemption Category | Details |
|---|---|
| Certain religious groups | Members of qualifying sects that are conscientiously opposed to SS benefits (Form 4029) |
| Nonresident aliens on certain visas | F-1, J-1, M-1, Q visas for services performed in student/exchange capacity |
| Student FICA exception | Students working for their own school are exempt from FICA if enrolled at least half-time |
| State/local government employees | Some covered by alternative public pension plans, varies by state |
| Foreign government employees | Generally exempt |
Overpayment: What Happens If You Work Multiple Jobs?
Each employer withholds OASDI independently. If total wages from two or more employers exceed the wage base, you overpay OASDI. You claim the overpayment as a credit on Form 1040, Line 11. Your employer's share is not refunded, only the employee excess is.
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Frequently Asked Questions
Is OASDI tax the same as Social Security tax?
Yes. OASDI and Social Security tax are identical. The IRS sometimes uses OASDI; pay stubs often say Social Security or FICA-SS.
Does OASDI contribute to retirement benefits?
Yes. OASDI taxes fund the Social Security trust funds. Your lifetime earnings record (used to calculate your future benefit) is built from wages on which OASDI tax was paid.
Can I opt out of OASDI as an employee?
Almost never. The religious and student exemptions are narrow and require IRS approval. Most employees cannot opt out.
How is this different for somebody who is self-employed?
They carry both halves, because there is no employer to pay the other part, and it is calculated through the return rather than deducted from a payslip. A portion is generally allowed as a deduction in computing income, which softens the effect but does not remove it. The practical consequence is that somebody moving from employment to self-employment sees a larger obligation on the same earnings, and it is the most common budgeting shock in the first year.
Does paying more increase what is eventually received?
Up to a point, and the relationship is not proportional. Benefits are calculated from a record of earnings across a working life, using a formula that replaces a higher share of lower earnings than of higher ones, and earnings above the annual cap neither attract the charge nor count toward the calculation. Checking your own earnings record periodically is worthwhile, since an error in it affects the eventual entitlement.
Written by
Anu Gupta, CA, EA, B.Tech
Anu works with US businesses on tax and entity questions at Profitjets, from choosing a structure to the filings that follow it. She writes about the decisions owners make once and then live with for years. Connect on LinkedIn
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