Q3 estimated taxes are due September 15 — here's the five-week plan
The third estimated tax payment of 2026 is due September 15 — five weeks out. It covers what you earned from June 1 through August 31, and if you've been setting money aside as you drive, this is the easy quarter: find the number, schedule the payment, forget about it.
Find your number in one export
The base is net profit for the window — earnings minus mileage cost minus tracked expenses, not your gross. Pull June 1–August 31 in your tax report and the subtraction is already done. Multiply by 25–30% and that's the payment: the 15.3% self-employment tax plus your income-tax bracket, covered. The reasoning behind that range is in the full quarterly system.
If the summer slowdown shrank your profit, it shrank your payment too — the percentage does the adjusting. A slow quarter owes less. That's the system working, not you falling behind.
Hate estimating? Use the safe harbor
Pay one quarter of 100% of last year's total tax each period (110% for higher incomes) and you're generally protected from the underpayment penalty no matter how 2026 turns out. If last year's return is handy, this turns the whole exercise into division.
The tips deduction doesn't cancel this payment
The new deduction can shelter up to $25,000 of tips from federal income tax — but every tip dollar still owes the 15.3% self-employment tax, and SE tax is a big share of what these quarterly payments cover. Skipping Q3 because "tips are tax-free now" is how April gets ugly. The full rules, explained.
Ten minutes, three steps
Export June 1–August 31 from your tax report and take the net profit line.
Multiply by your rate. 25% if your mileage deduction is heavy, closer to 30% if your state taxes income too.
Schedule it on IRS Direct Pay today, dated September 15. It pays itself while you're out driving.
Behind on the set-aside? A partial payment on time still beats a full payment in April — the penalty accrues quarter by quarter, so every on-time dollar stops its own meter.
Where GigReal fits: net profit for any date range is one export away — earnings, mileage at the IRS rate, and expenses already netted. Q3 is a filter, a multiply, and a payment.
General information, not tax advice. Deadlines shift on weekends and holidays, states run their own estimated-payment systems, and safe-harbor details depend on your prior-year return — confirm your situation with a tax professional or IRS.gov.
