Quarterly estimated tax calculator for freelancers
Hit the safe harbour target and the underpayment penalty does not apply.
If you are self-employed in the US, nobody withholds tax from your invoices — which means you are expected to pay it four times a year. Get it wrong and the IRS charges interest on the shortfall.
The good news is that you do not have to predict your income accurately. You only have to hit a safe harbour target, and this calculator works out what that target is, what is left to pay, and roughly what falling short would cost you.
The rule that stops the penalty
The IRS does not require you to predict your income perfectly. It requires you to pay enough throughout the year to hit one of two targets, and if you hit either one you are protected from the underpayment penalty even if you end up owing tax in April.
Those two targets are:
- 90% of what you actually owe this year, or
- 100% of what you owed last year — rising to 110% if your prior-year adjusted gross income was over $150,000.
Whichever is smaller is your safe harbour number, and that is the figure this calculator reports. Pay it in instalments across the year and the penalty does not apply. This is why the prior-year figure matters so much: in a year when your income jumps, last year's tax bill is usually the cheaper target, and it is often dramatically cheaper.
When the payments are due
Estimated tax is paid in four instalments, and the dates are not evenly spaced:
- 15 April — for income earned 1 January to 31 March
- 15 June — for 1 April to 31 May (a two-month period)
- 15 September — for 1 June to 31 August (three months)
- 15 January — for 1 September to 31 December (four months)
If a due date falls on a weekend or holiday it moves to the next business day. Miss one and the penalty starts accruing on that instalment specifically — which is why catching up later in the year does not fully undo an early miss.
Why freelancers get caught out
Three patterns account for most underpayment penalties.
Irregular income
Estimated tax assumes you can predict the year. A freelancer who earns nothing for five months and then lands a $40,000 project in June cannot have known that in April. The fix is the annualised income method on Form 2210, Schedule AI, which lets you match instalments to when the money actually arrived. It is more paperwork, but it can eliminate a penalty that would otherwise be owed.
Assuming the employer is still withholding
If you have a W-2 job alongside freelance income, increasing withholding on your W-4 is usually easier and more forgiving than making quarterly payments. Withholding is treated as having been paid evenly throughout the year regardless of when it was actually taken, which gives you far more flexibility than estimated payments.
Treating a good quarter as a new baseline
One strong quarter is not a run rate. Freelancers who extrapolate a good three months into an annual figure and pay accordingly often overpay — which is harmless but annoying, because getting the money back means waiting for a refund.
How big the penalty actually is
The underpayment penalty is not a fixed fine. It is interest, calculated per instalment on Form 2210, at the federal short-term rate plus three percentage points, compounded daily. In recent years that has worked out to somewhere between 7% and 10% annualised.
The figure in this calculator is a rough average, not a Form 2210 computation. Because interest accrues separately on each missed instalment, the real number depends on exactly which payments you missed and when you caught up. A shortfall that persisted from April costs roughly twice what one from September costs. If the estimate here is significant, run the actual form or have your accountant do it.
Worth knowing: the penalty is computed on the shortfall, not on your total tax. Owing $8,000 in April is not itself a problem. Owing $8,000 when the safe harbour required you to have prepaid it is.
Setting aside money the easy way
The mechanics that actually work are unglamorous. Open a separate savings account, transfer a fixed percentage of every payment that arrives — 25% to 30% covers most freelancers once self-employment and income tax are combined — and never look at it as available money. Because a large share of freelance income arrives without any withholding, the discipline of moving it out of your current account on receipt is what prevents the April surprise.
If your income is genuinely unpredictable, consider paying the safe harbour amount based on last year rather than trying to estimate this year. It is a fixed, knowable target, it protects you from the penalty, and if you earn less than expected you will simply get a refund.
Estimates for the 2025 tax year, federal only. State estimated tax is separate and has its own rules and thresholds. This calculator ignores the QBI deduction, credits, and any W-2 income or withholding. Figures are illustrative — see the disclaimer and confirm current-year amounts with the IRS Topic 554 — Self-Employment Tax.
Frequently asked questions
Do I have to pay estimated tax if I am self-employed?
Generally yes, if you expect to owe at least $1,000 in tax for the year after subtracting withholding and credits. Unlike employment income, nothing is withheld from freelance payments, so the IRS expects you to pay as you earn rather than settling everything the following April.
What happens if I miss a quarterly payment?
You will likely owe an underpayment penalty, which is interest rather than a fixed fine — the federal short-term rate plus three percentage points, accruing daily on each missed instalment. Catching up later reduces but does not erase it, because interest has already accrued on the period you were short.
What is the safe harbour rule?
Pay either 90% of the current year tax or 100% of the prior year tax — 110% if your prior-year AGI exceeded $150,000 — and you are protected from the underpayment penalty even if you ultimately owe more. Whichever figure is smaller is your target, which makes last year bill a useful anchor when income jumps.
How much should I set aside from each freelance payment?
Between 25% and 30% is a workable starting point for most US freelancers, covering both self-employment tax and federal income tax at moderate incomes. Above roughly $150,000 you will want more; if you have significant deductions, retirement contributions or a spouse with withholding, you may need less.
Can I pay estimated tax annually instead of quarterly?
Not without risking the penalty. The requirement is to pay as income is earned, spread across four instalments with uneven period lengths. If your income is very irregular, the annualised income method on Form 2210 lets you match payments to when you actually earned the money.
Is it better to increase W-2 withholding instead?
If you or your spouse have a W-2 job, often yes. Withholding is treated as paid evenly through the year no matter when it was actually taken, which gives you much more flexibility than estimated payments and lets you adjust late in the year to cover a surprise. It is the simplest way to hit a safe harbour target.