Tax year 2026 · Federal estimates

Q3 estimated tax calculator

September 15 is the next IRS due date. See if you’re short. Built for self-employed, 1099, and S-corp owners who need a rough federal number — not a return.

Q3 due Tue, Sep 15, 2026 Q4 due Fri, Jan 15, 2027 Today: Fri, Aug 14, 2026

Your numbers

Use net profit after ordinary business expenses, before owner draws. If you only know year-to-date, we’ll annualize it.

This profit figure is

Expected full year Year-to-date

Self-employment / business profit (USD) Schedule C net profit, or S-corp ordinary income if that’s what you have. Not gross receipts.

Expected 2026 W-2 / other withholding Full-year federal income tax withheld, if any. Optional. This credits the tax already being withheld. It does not add W-2 wages into the income stack, so a large W-2 can mean the rate on your business profit is understated. Federal estimates already paid (Q1 + Q2) 1040-ES payments sent for 2026 so far. Not state.

Filing status

Single Married filing jointly

S-corp?

No Yes

State income tax (rough) State is a side estimate only. It is not added into the federal Q3 figure. Local taxes are ignored. Last year’s total federal tax (optional, for safe harbor) Usually Form 1040 “total tax” from your 2025 return. Used only for the penalty safe-harbor math. Last year’s AGI was over $150,000 ($75,000 if married filing separately). If so, safe harbor is 110% of last year’s tax, not 100%.

Enter a profit figure to see a rough Q3 number.

2026 estimated tax calendar

Federal 1040-ES dates for tax year 2026. Q1 and Q2 have already passed.

Q1Due Apr 15, 2026Past

Q2Due Jun 15, 2026Past

Q3Due Sep 15, 2026Next — 32 days from Aug 14

Q4Due Jan 15, 2027Or file the 2026 return and pay in full by Feb 1, 2027

How this estimate is built

2026 federal brackets and standard deduction ($16,100 single / $32,200 MFJ) from IRS inflation adjustments for tax year 2026.
Self-employment tax: 15.3% on 92.35% of net profit (12.4% Social Security up to a $184,500 wage base, 2.9% Medicare on all net earnings). Half of SE tax is deducted before income tax.
Additional 0.9% Medicare tax on SE earnings over $200,000 (single) or $250,000 (MFJ). W-2 wages are not an input and are not stacked on business profit — only withholding is credited — so both the income-tax bracket and Additional Medicare tax can be understated if you have a large W-2.
No QBI (199A) deduction, no itemizing, no credits, no NIIT, no self-employed health insurance or retirement contributions. Skipping QBI usually overstates tax a bit, which is safer for “am I short?”
Withholding is treated as paid evenly over the year, so 75% is counted as in by September 15.
Suggested Q3 is the amount needed so that estimates already paid plus deemed withholding equal 75% of the penalty-avoidance target (90% of this year’s estimated tax, or the lower of that and safe harbor if you entered last year’s tax).
S-corp mode skips SE tax on the profit figure. That is not how a real return works if salary is too low.

This is an estimate, not advice. Picnic Tax is not your CPA because you used this page. Underpayment penalties, annualized income, multi-state sourcing, reasonable S-corp compensation, and QBI can change the real number by a lot. Pay through IRS Direct Pay or EFTPS; keep the confirmation.

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