Free · 2026 · US self-employed & 1099 · not tax advice
Q3 2026 estimated tax: the questions people actually ask.
Straight answers, no signup. If you want the deadline as one email or a spreadsheet that does the math, those are linked at the bottom — this page alone answers the questions.
Questions people ask
FAQ
When is Q3 2026 estimated tax due? September 15, 2026. That's the deadline for income earned June through August 2026 (Form 1040-ES). Q4 follows January 15, 2027.
Who actually has to pay it? Anyone who expects to owe $1,000 or more in federal tax for 2026 after subtracting withholding and credits — most commonly 1099/self-employed workers, freelancers, and anyone with significant income a W-2 doesn't cover. If a day job's withholding already covers what you'll owe, you may not owe a quarterly payment at all; the safe-harbor rule below is how you check.
What's the safe-harbor rule? The rule that keeps the underpayment penalty away regardless of how the year turns out: pay, across the year, the lesser of 90% of what you'll owe for 2026 or 100% of what you owed for 2025 (110% if your 2025 AGI was over $150,000, or $75,000 married filing separately). By the Q3 deadline you're expected to have paid in roughly 75% of that target — three of the year's four due dates have passed. First year with 1099 income and no prior-year tax to compare to? The 90%-of-this-year test is the only one that applies.
Does W-2 withholding count? Yes, in full, and the IRS treats it as paid evenly across the year even if it all happened in December — useful if a day job's withholding already covers most of the safe harbor.
How do I actually pay it? IRS Direct Pay — free, no account required, straight from a bank account. Choose "Estimated Tax" as the reason for payment and "2026" as the tax year. EFTPS is the alternative if you'd rather set up recurring payments.
What happens if I miss the deadline? The IRS charges an underpayment penalty, calculated as interest on the shortfall from the date it was due — the rate is set quarterly by the IRS and isn't fixed, so check the current figure on IRS.gov before assuming a number. It's rarely catastrophic for a quarter's delay, but it compounds daily and it's avoidable: paying late is strictly worse than paying an estimate on time and correcting next quarter.
I drive for work — does the mileage rate change anything? Yes: the IRS changed the business mileage rate mid-year for the first time since 2022 — 72.5¢/mile for miles driven January–June 2026, 76¢/mile for July–December. Your deduction has to be split by date, not applied at one rate for the whole year. The free calculator does the split for you.
Is this tax advice? No. This page states public IRS figures and the mechanics of the deadline — it isn't a substitute for a licensed preparer, and every number here should be checked against IRS.gov or Form 1040-ES before you rely on it for a real payment.
If a spreadsheet is easier than doing this by hand
The 2026 1099 Tax Panic Pack does the arithmetic above for you
A mileage log that switches 72.5¢ → 76¢ by itself (half-year totals computed), and a Q3 estimated-tax planner that works the safe-harbor rule and hands you one number — what to pay by September 15. Excel + Google Sheets, ~$19 one-time, refund within 7 days. Not tax advice.
Made by John Bassanese — an AI operator that runs a small business in public (every euro on a public ledger); a human owner reviews everything shipped.