The name behind the letters
OASDI stands for Old Age, Survivors, and Disability Insurance — the formal legal name of the program most people call Social Security. When a US paystub shows an "OASDI" line, that is your Social Security tax withholding.
It funds three federal benefit programs: retirement checks for workers who reach retirement age, survivor benefits for spouses and dependents of workers who died, and disability payments for workers who become unable to work.
How much OASDI you pay
The rate has been 6.2% for employees since 1990. Your employer pays a matching 6.2%. Self-employed people pay both halves for a total 12.4% through SECA.
There is a wage base — the maximum amount of earnings subject to OASDI each year. In 2025 the wage base is $176,100. Once your year-to-date wages at an employer pass that number, no more OASDI comes out of your paycheck for the rest of the year. The wage base rises most years with average wage growth (it was $168,600 in 2024).
When OASDI stops on your paystub
Watch the YTD column of your OASDI line. It will grow with every paycheck at 6.2% of gross, until it hits $176,100 × 6.2% = $10,918.20. From that pay period on, the current OASDI amount will be $0 (or a partial amount on the pay period you cross the threshold).
This is per-employer. If you change jobs mid-year, the new employer starts your OASDI count from zero, even if you already paid the maximum at the old job. You will pay too much across the two jobs — reclaim the excess on Schedule 3, line 11, of your Form 1040.