Self-Employment Tax 2027 Quarterly Estimate Calculator
Estimate your 2027 self-employment tax (15.3% combined) and quarterly Form 1040-ES payments to avoid underpayment penalties.
2027 SE Tax Mechanics
Self-employment tax = 12.4% Social Security + 2.9% Medicare = 15.3% combined on 92.35% of net SE earnings (the 92.35% adjusts for the employer-equivalent half). 2027 Social Security wage base projected ~$176,100 — earnings above this get only Medicare (2.9%). Income above $200K single / $250K MFJ also triggers an additional 0.9% Medicare. Source: IRC §1401, Rev. Proc. 2024-40. Last updated: May 2026.
Quarterly Estimated Tax Deadlines
Form 1040-ES quarterly payments are due: Q1 — April 15, 2027 (income Jan-Mar); Q2 — June 15, 2027 (Apr-May); Q3 — September 15, 2027 (Jun-Aug); Q4 — January 15, 2028 (Sep-Dec). Missing or underpaying triggers Form 2210 underpayment penalty (currently ~8% APR — IRS interest rate).
Safe Harbor: Avoid Penalties Two Ways
Pay at least the LESSER of: (a) 90% of current year's tax, or (b) 100% of last year's tax (110% if last year's AGI exceeded $150K). Most self-employed taxpayers use the prior-year safe harbor because it's predictable. Mark your calendar with all four deadlines — late penalty applies even if you overpay by year-end.
Deduction: Half of SE Tax
You get to deduct HALF of your SE tax as an above-the-line adjustment (Schedule 1 line 15) — the deemed 'employer portion'. This reduces AGI but not SE tax itself. On $80K net SE profit, SE tax is $11,304, of which $5,652 is deductible. This adjustment is independent of itemizing.