Self-Employment Tax Calculator
15.3% is the headline, not the whole story. See exactly where it comes from — 12.4% Social Security (capped), 2.9% Medicare (not capped), and any 0.9% additional Medicare — then get your quarterly number.
Never chase a W-9 again
Our $24 1099 Contractor Tracker keeps every 1099, expense, and quarterly payment organized all year. Get the free W-9 chase checklist:
Common questions
Why isn't self-employment tax just 15.3% of everything?
15.3% is the headline, not the whole story. Social Security's 12.4% only applies to the first $184,500 of net earnings in 2026, while the 2.9% Medicare portion has no cap — and the math starts from 92.35% of net earnings, not 100%.
What's the 0.9% additional Medicare tax?
An extra 0.9% on net earnings above $200,000 single or $250,000 joint in 2026. The calculator adds it automatically when your earnings cross the threshold.
Do I owe SE tax on a small side gig?
No SE tax under $400 net earnings. Above that it applies — and the good news is that half of what you pay is deductible against your income tax.