Your quarterly estimated payment is your total expected tax for the year, minus any withholding already covered, divided by four. For 2026 the four due dates are April 15, June 15, and September 15 of 2026, and January 15 of 2027. This calculator estimates the full tax — self-employment, federal, and state — then splits what's left into those four payments.
Why the IRS wants four payments instead of one
The US tax system is pay-as-you-go. Employees never notice, because their employer withholds a slice of every paycheck and sends it in continuously. The IRS expects the same rhythm from the self-employed — it just can't withhold from you, so it asks you to send the money yourself, four times a year, in roughly equal installments.
Skip the rhythm and two things happen. First, the practical one: a full year's tax bill landing in a single April is a cash-flow crisis for most freelancers, because the money was spent months ago on things that felt necessary at the time. Second, the formal one: the IRS charges an underpayment penalty — effectively interest on the shortfall — when your payments fall too far behind your income. The penalty is rarely devastating, but it is pure waste: money paid for the privilege of paying late.
The freelancers who handle this well treat the quarterly payment as a bill that arrives four times a year, sized by a calculator like this one and funded by a separate savings account they feed from every invoice. Boring, mechanical, and completely effective.
How this calculator works
This tool runs the identical 2026 tax engine as our Self-Employment Tax Estimator — same brackets, same $184,500 Social Security wage base, same state rate table — so the two tools always agree on the same income. If you want the component-by-component breakdown, the estimator shows it; this page focuses on the payment schedule:
- Total annual tax: self-employment tax (15.3% on 92.35% of net earnings, Social Security capped at the wage base, plus the 0.9% additional Medicare tax at higher incomes), plus federal income tax after the standard deduction, plus a state planning estimate.
- Subtract what's already covered: W-2 withholding — yours from a day job, or a spouse's if you file jointly — counts toward the same obligation. So do any estimated payments you've already sent this year.
- Divide by four: the remainder is split across the four due dates in equal installments — with any rounding remainder landing in the final payment, the way Form 1040-ES handles it, so the four payments always add up to the exact remainder. Equal installments are the simplest schedule the IRS accepts, and the one this calculator produces.
Worked example
Alex is a single freelance developer in Texas expecting $80,000 of net self-employment income in 2026. Alex also picks up part-time W-2 work on the side and expects $1,200 of federal withholding from that job to count toward the same obligation:
- Total estimated 2026 tax: $18,830.24 (SE tax $11,303.64 + federal $7,526.60 + Texas state tax $0 — the same figures the SE Tax Estimator produces for this income)
- Less withholding already covered: −$1,200.00
- Remaining to pay through estimates: $17,630.24
- Quarterly payment: $4,407.56 — due Apr 15, Jun 15, Sep 15, 2026 and Jan 15, 2027
That withholding field is doing quiet, powerful work: every dollar of W-2 withholding is a dollar Alex doesn't have to remember to send. Many freelancers who also hold a W-2 job deliberately raise the withholding at that job to shrink — or eliminate — their quarterly checks.
The safe harbor: your penalty insurance
You don't have to predict your income perfectly to avoid penalties — you have to clear a lower bar. The IRS generally waives the underpayment penalty if your total payments for the year reach either 90% of the tax you actually owe for 2026, or 100% of last year's total tax (that second threshold rises to 110% if your prior-year adjusted gross income was over $150,000). This is the safe harbor rule.
Its practical consequence: if last year's tax bill is easy to reach, base your quarterly payments on it and stop forecasting. Income jumped this year? The safe harbor still shields you — you'll settle the difference in April, penalty-free. Income dropped? Then paying on last year's figure overpays, and you'd rather run this calculator on your lower projection and meet the 90%-of-actual bar instead. Either way, aim deliberately at one of the two targets rather than guessing.
When your income is uneven
Equal installments assume income arrives evenly, and freelance income rarely does. If most of your money lands in the second half of the year, equal early payments can overpay early and strain cash flow; if it lands early, equal payments can underpay the early quarters. The IRS answer is the annualized income installment method (Form 2210, Schedule AI), which matches each payment to the income actually earned by that point in the year. It's more paperwork at filing time, but it can erase penalties that the simple ÷4 schedule would have triggered for seasonal earners. This calculator gives you the standard equal-installment figure — the right default for steady income, and the baseline to compare against if your year is lumpy.