Quarterly Tax Estimator — Calculate Your IRS Estimated Payments

The IRS requires self-employed workers and anyone without sufficient tax withholding to pay estimated taxes four times a year rather than in one lump sum at filing time. This calculator estimates your total annual tax liability — combining self-employment tax and federal income tax across all income sources, including any other income beyond your self-employment earnings — then splits the remaining balance evenly across the four quarterly due dates, accounting for any payments you have already made this year.

How to use this Quarterly Tax Estimator

1. 1Enter your estimated annual self-employment or 1099 income.
2. 2Enter your business expenses to calculate net self-employment profit.
3. 3Enter any other income for the year — W-2 wages, interest, or other taxable income not subject to self-employment tax.
4. 4Enter any tax already paid this year, such as prior quarterly payments or W-2 withholding.
5. 5Read your estimated annual tax, remaining balance owed, and the per-quarter payment amount with each due date.

Quarterly estimated tax formula explained

Total annual tax combines self-employment tax (calculated only on net self-employment income, not other income) with federal income tax on combined taxable income from all sources. After subtracting any tax already paid during the year — through withholding or prior quarterly payments — the remaining balance is divided evenly across the four remaining quarterly due dates to determine each payment amount.

Quarterly estimate: $80,000 self-employment income, $10,000 expenses, no other income

1. 01Net self-employment income: $80,000 − $10,000 = $70,000.
2. 02Self-employment tax: $70,000 × 0.9235 × 15.3% = $9,890.68.
3. 03Taxable income (after SE tax deduction and standard deduction): $50,454.66.
4. 04Federal income tax on $50,454.66: $6,153.02.
5. 05Total estimated annual tax: $9,890.68 + $6,153.02 = $16,043.71.
6. 06Per-quarter payment (no prior payments made): $16,043.71 ÷ 4 = $4,010.93.

What determines your quarterly tax payment amount?

Tips and things to know

• ✓Recalculate your remaining quarterly payments each quarter using actual year-to-date income rather than a flat estimate, especially if self-employment income is variable month to month.
• ✓If you also have a W-2 job, consider increasing your W-2 withholding instead of making separate quarterly payments — withholding is treated as paid evenly throughout the year by the IRS regardless of when it was actually withheld, which can simplify your tax situation.
• ✓Mark all four due dates in a calendar with a reminder, since missing a quarterly deadline can trigger penalty interest even if the total annual tax is eventually paid in full.
• ✓The "safe harbor" rule — paying 100% of last year's total tax liability (110% if your prior year adjusted gross income was over $150,000) — guarantees no underpayment penalty regardless of how much you actually owe this year, which can simplify planning during a year with unpredictable income.
• ✓Use IRS Form 1040-ES to make official quarterly payments, either by mail or through the IRS's online payment system (IRS Direct Pay or EFTPS), and keep confirmation records of each payment.

Quarterly Tax Estimator — bottom line

Quarterly estimated tax payments exist because the US tax system is pay-as-you-go — taxes are supposed to be paid roughly when income is earned, not as a lump sum in April. For W-2 employees, employers handle this automatically via withholding. For freelancers, self-employed workers, business owners, landlords, and investors with significant unearned income, estimated payments are the mechanism. Miss them and you face an underpayment penalty — not just a bill in April, but a penalty on top of the balance owed. The due dates are April 15, June 15, September 15, and January 15 (for Q4 of the previous year). Missing the January 15 deadline is the most common miss because it follows the holiday season. Set a recurring calendar reminder for all four. The most common mistake is estimating quarterly payments based on the previous quarter's income rather than projecting the full year. The IRS penalty is based on your annual liability, not quarterly income. If your income is seasonal or lumpy, model the full-year income and divide equally across four quarters — then check whether you qualify for the annualized income installment method. Second mistake: paying exactly what you calculate without any buffer. A 5–10% overpayment on each quarter means a small refund at filing rather than a balance due — psychologically much easier and eliminates any risk of underpayment penalty. The safe harbor rule: if you pay at least 100% of last year's total tax liability (110% if your prior-year AGI exceeded $150,000) in estimated payments, you avoid the underpayment penalty regardless of what you owe at filing.

Official resources and further reading