The Social Security wage base is the ceiling on wages that the 6.2% Social Security tax applies to. In 2026 it is $184,500. Once your wages for the year pass that number, the Social Security line on your pay stub drops to zero for the remaining pay periods, and your take-home pay rises by 6.2% until January, when the count starts over.
The effect is visible. Someone earning $240,000 crosses the base in roughly the tenth month. Their last few paychecks are noticeably larger, by about $600 per biweekly check, and then shrink again in the new year. People who receive a large bonus or vest early in the year cross even sooner.
The wage base matters in three planning situations. First, budgeting: late-year paychecks are not the right baseline for next January. Second, job changes: if you switch employers mid-year, the new employer starts counting from zero and may over-withhold; the excess comes back as a credit on your tax return. Third, self-employment: the cap applies to combined wages and self-employment income, so a side business on top of a high salary may owe no Social Security tax at all.
The cap rises most years with average wage growth. Medicare has no equivalent cap, and the 0.9% additional Medicare tax begins at $200,000 regardless.