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.
Frequently Asked Questions
What's the 2027 SE tax rate?
15.3% combined: 12.4% Social Security (on first $176,100 projected wage base) + 2.9% Medicare (no income cap). Applied to 92.35% of net SE earnings. Income above $200K single / $250K MFJ adds another 0.9% Additional Medicare Tax.
When are 2027 quarterly estimated taxes due?
Four deadlines: April 15, 2027 (Q1, Jan-Mar income); June 15, 2027 (Q2, Apr-May); September 15, 2027 (Q3, Jun-Aug); January 15, 2028 (Q4, Sep-Dec). If a deadline falls on a weekend or holiday, the deadline shifts to the next business day.
How do I avoid the underpayment penalty?
Use the safe harbor: pay at least the LESSER of (a) 90% of 2027 total tax, or (b) 100% of 2026 total tax (110% if your 2026 AGI exceeded $150K). Most self-employed taxpayers pay 100/110% of prior year because it's predictable and avoids needing accurate current-year projections.
Can I deduct any of the SE tax I pay?
Yes \u2014 you get an above-the-line deduction for HALF of your SE tax (the deemed employer portion). Claim on Schedule 1 line 15. This reduces AGI but doesn't reduce SE tax itself. The deduction is permanent (not affected by OBBB or other tax changes).
Does W-2 income affect my SE tax?
Yes \u2014 W-2 wages count toward the Social Security wage base. If you earn $100K W-2 and have $80K SE, only the first $76,100 of SE earnings ($176,100 minus $100K W-2) is subject to the 12.4% SS portion. The 2.9% Medicare portion has no cap and applies to all SE earnings.
Can S corp owners avoid SE tax?
Partially. S corp shareholders pay FICA only on W-2 reasonable compensation, not on K-1 distributions. So a $200K S corp profit split as $100K salary + $100K K-1 = $7,650 saved vs full SE tax on $200K. But IRS scrutinizes 'reasonable comp' \u2014 too-low salary triggers audit and reclassification.