OASDI is the line taking 6.2% of your gross pay, and it is Social Security under a different name. For most people the interesting question is not what the letters stand for. It is whether the thing ever stops. It does, at $184,500 of wages in 2026, and if you earn more than that your paychecks get visibly bigger part way through the year.
What the letters mean, briefly
Old-Age, Survivors, and Disability Insurance. That is the formal name for the Social Security program, so OASDI on a pay stub is the Social Security tax and nothing else. It is one of the two halves of FICA. Payroll systems label it inconsistently, which is most of why it causes confusion. OASDI, FICA-OASDI, Soc Sec, SS and Social Security Tax are all the same deduction, and you should only ever see one of them.
You pay 6.2% and your employer pays another 6.2% that never appears on your stub, so the program collects 12.4% of your wages in total. If you are self-employed you pay both halves yourself.
The number it stops at
Social Security is charged on a capped amount of earnings, which the Social Security Administration calls the contribution and benefit base and everyone else calls the wage base. For 2026 it is $184,500, up from $176,100 in 2025.
- The most OASDI anyone can pay in 2026 is $11,439.00, which is 6.2% of $184,500.
- Once your wages for the year reach the base, the line disappears from your stub until January.
- It resets on the 1st of January, every year, for everybody.
- Medicare does not stop. There has been no wage limit on Medicare since 1993, so that line keeps coming off every check all year, and above $200,000 it gets larger rather than smaller. Fed MED/EE and Fed MWT/EE covers that side.
What month it stops, by salary
Divide the wage base by your salary and you have the fraction of the year you spend paying it. On $300,000 that is 61.5% of the year, which lands in August.
| Annual salary | Roughly when it stops | Checks with no OASDI | Each of those is bigger by |
|---|---|---|---|
| $184,500 or less | It never stops | none | nothing |
| $200,000 | early December | 2 | $476.92 |
| $250,000 | late September | 6 | $596.15 |
| $300,000 | mid-August | 10 | $715.38 |
| $400,000 | mid-June | 14 | $953.85 |
| $500,000 | mid-May | 16 | $1,192.31 |
The check the cap falls in is a partial one, where OASDI comes off part of the pay and not the rest. Everything after it is clean.
Why your November paycheck is suddenly bigger
This is the question behind most searches for OASDI, and the answer is dull in the best way. It is not a raise, it is not a payroll error, and nobody has forgotten to deduct something. You reached the wage base, so there is nothing left to charge.
The trap is treating the bigger check as the new normal. On $300,000 paid every two weeks, the last ten checks of the year each arrive $715 heavier, which is around $7,000 landing in the autumn. Then January comes, the base resets, and the check shrinks back to its old size. People who moved a standing payment up to match the bigger figure spend the first quarter wondering what went wrong. If you want that money to do something, decide in August rather than discovering it in November.
What counts toward the $184,500, and what does not
Not every pre-tax deduction is pre-tax in the same way, and this is where two people on identical salaries hit the cap in different weeks.
- A 401(k) contribution does not reduce it. Elective salary deferrals are exempt from federal income tax withholding but not from Social Security or Medicare. On your W-2 they are left out of box 1 and included in boxes 3 and 5. Putting $1,000 a month into a 401(k) lowers your income tax and changes your OASDI by nothing at all, which what a 401(k) actually costs your paycheck works through in dollars.
- Section 125 deductions do reduce it. Health insurance premiums taken by salary reduction, along with an FSA and most HSA contributions run through payroll, come out before Social Security and Medicare as well as before income tax.
Worked through: someone on $200,000 paid every two weeks reaches the base during their 24th check, and the last two of the year arrive without OASDI. Give the same person $500 a pay period of health premiums and their Social Security wages drop to $187,000 for the year, which pushes the cap into the 26th check and leaves them none. A $500 a period 401(k) deferral, by contrast, moves the date not at all.
The take-home pay calculator keeps those three deductions in separate fields for exactly this reason, and shows the OASDI line for your first check of the year alongside the annual figure.
If you changed jobs, you may have overpaid
Each employer applies the wage base on its own, and no employer knows what the last one withheld. Two jobs in one year adding up to more than $184,500 means more OASDI came out than was owed, sometimes by thousands.
You get it back, but not from payroll. The IRS treats the excess as a credit you claim on your own return against your income tax, and the money comes back with your refund. What you cannot do is ask either employer to fix it, because neither of them did anything wrong.
The one exception is a single employer withholding too much on its own, which is an error rather than an artifact of two jobs. That one your employer is supposed to adjust, and if they will not, the IRS has a separate form for it. Either way it is worth checking the box 4 figure on every W-2 in a year you changed jobs.
Frequently asked
The Social Security tax. OASDI stands for Old-Age, Survivors, and Disability Insurance, which is the formal name of the Social Security program. It takes 6.2 percent of your wages, your employer pays another 6.2 percent you never see, and some pay stubs label the same line FICA-OASDI, Soc Sec or SS.
When your wages for the year reach $184,500 in 2026. On a $300,000 salary that is around mid-August, on $200,000 it is early December, and at $184,500 or below it never stops. It resets every January 1.
$11,439.00, which is 6.2 percent of the $184,500 wage base. That is the most any one person can pay in a year, and the base rose from $176,100 in 2025.
If you earn more than the wage base, you most likely reached it and OASDI stopped. The check will shrink back in January when the base resets, so it is worth treating the extra as a few months of windfall rather than a new baseline.
No. Elective 401(k) deferrals are exempt from federal income tax withholding but not from Social Security or Medicare, which is why they appear in boxes 3 and 5 of your W-2 but not box 1. Section 125 health premiums do reduce it.
Yes, on your tax return rather than from payroll. Each employer applies the wage base separately, so two jobs together can push you over it. The IRS treats the excess as a credit against your income tax. A single employer withholding too much is a different case and that one the employer is meant to correct.