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.
Paying Quarterly Estimates: Methods, Proof, and the Annualized Option
Knowing the amount is half the job; the penalty usually comes from how and when it was paid. Payments can be made electronically through IRS Direct Pay or EFTPS, or by mail with Form 1040-ES vouchers, and the IRS estimated taxes guidance treats the payment date as the date of the electronic transaction or the postmark. Keep the confirmation number — a misapplied payment is far easier to fix with one. Three points matter for irregular income. Estimated-tax penalties are computed period by period, so a large fourth-quarter payment does not cure an underpaid first quarter; the shortfall in each period accrues its own interest-style charge. If income arrives unevenly, the annualized income installment method lets you match payments to when the income was actually earned instead of paying four equal amounts, which is the standard fix for seasonal or project-based work. And if you also hold a W-2 job, increasing withholding there is treated as paid evenly across the year, which can retroactively cover an earlier quarter in a way an estimated payment cannot. Updated 2026-09-14.
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 — 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 — 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' — too-low salary triggers audit and reclassification.
Can I just pay all my estimated tax in the fourth quarter?
No — the penalty is calculated period by period, so an underpaid first quarter still accrues a charge even if the year-end total is correct. If your income genuinely arrives late in the year, use the annualized income installment method so payments are matched to when the income was earned. If you also have a W-2 job, extra withholding there is treated as paid evenly across the year and can cover an earlier quarter in a way a late estimated payment cannot.
How do I pay quarterly estimated taxes and prove I paid on time?
Pay electronically through IRS Direct Pay or EFTPS, or by mail with Form 1040-ES vouchers. The payment date is the electronic transaction date or the postmark, so keep the confirmation number or mailing proof — it is what resolves a misapplied or late-credited payment. Electronic payment also avoids the most common failure mode, which is a voucher credited to the wrong tax year.