The IRS wants $4,708 four times a year. Set it to move automatically on the due dates and the penalty question never comes up.
How estimated tax payments work
The IRS requires advance payments if you expect to owe $1,000 or more in tax for the year. You estimate the tax, divide by four, and pay on the quarterly due dates. Underpay, and you owe interest and penalties even if your final return shows you paid enough in the end.
The safe-harbour rule is worth knowing: if you pay at least 90% of the tax shown on your current year return, or 100% of the prior year’s tax (110% if your prior-year AGI was over $150,000), the IRS generally waives the penalty for underpayment. That gives high-income freelancers with a growing business a useful floor to fall back on.
This calculator applies the same self-employment tax and federal income tax brackets as the self-employment tax calculator, then adds a 10% buffer. It does not include state estimated tax, which is often a separate payment with separate deadlines.
How to use it
- Enter your expected annual profit. Base it on what you have actually invoiced so far plus what you have booked, rather than your best guess at the full year.
- Set aside the recommended figure, not the exact one. The 10% buffer covers the deductions you will forget, the rate you assumed slightly wrong, and the quarter where a big invoice lands later than expected.
- Put it somewhere separate. A separate savings account beats a mental note. The single most common cause of an underpayment penalty is spending the tax money because it was sitting in the everyday account.
The four due dates and what happens if you miss one
The quarters are not calendar quarters. For a calendar-year filer the payments are due in April, June, September and the following January — the June date is the one people most often miss, because it comes about two and a half months after the April payment rather than three.
Missing a date does not invalidate the payment. Interest accrues from the due date on the amount that was late, so paying two weeks late costs a small amount rather than the whole penalty. Skipping a quarter entirely and catching up at filing time is much more expensive.
The penalty itself is calculated at a short-term federal rate applied to each underpayment for the period it was outstanding. It is not a flat fine, which is why the advice to pay something on every due date is better than waiting until you can pay the right amount.
Frequently asked questions
What if my income changes during the year?
Re-run the calculator with your updated expected profit and adjust the remaining payments. You are allowed to revise your estimate mid-year; the safe-harbour rule then applies to the current year rather than the prior year.
Do I need to file Form 1040-ES?
Yes, generally, if you have quarterly income or are self-employed and expect to owe $1,000 or more. Payment vouchers and addresses are on the IRS site; sending the wrong amount of withholding can create a mismatch with your actual liability.