Self-employment tax calculator (2026)

How the number is built

Schedule SE does not tax your whole profit. It first multiplies net profit by 92.35%, which removes the employer-equivalent half of the tax from the base. If that result is under $400, there is no self-employment tax at all.

On what remains, two rates apply. Social Security is 12.4%, but only up to the 2026 wage base of $184,500, and wages you already earned at a job use up part of that base first. Medicare is 2.9% with no cap. Once your self-employment earnings pass your filing-status threshold ($200,000 single, $250,000 joint, $125,000 separate, reduced by any W-2 Medicare wages), an extra 0.9% Additional Medicare Tax applies on Form 8959.

Half of the regular self-employment tax comes back as an adjustment to income on Schedule 1. The 0.9% Additional Medicare Tax is not part of that deduction.

What this calculator leaves out

It covers one person's self-employment tax. Income tax is separate and usually larger, so the quarterly figure here is only the self-employment slice of what you should set aside. It does not handle church employee income, farm or non-farm optional methods, or combining two spouses' businesses. For a married couple, run it once per spouse who has self-employment income; if you file jointly, put your spouse's W-2 wages in the spouse field so the joint $250,000 threshold is reduced correctly. The one wage field stands in for both Social Security wages (box 3) and Medicare wages (box 5), which usually match unless you have certain pre-tax benefits. The step-by-step version, with worked examples at three profit levels, is in the Schedule SE guide.