Quarterly Estimated Tax Calculator 2026

What are quarterly estimated taxes?

The Quarterly Estimated Tax Calculator 2026 helps you estimate federal tax payments during the year. If you earn business income without enough tax withheld, you may need to pay income tax and self-employment tax directly to the IRS.

Your estimate is not your final tax bill. It is a way to pay toward the tax you expect to owe and check whether your withholding and estimated payments meet a safe-harbor target. Your actual tax can change with income, deductions, credits and other details on your return.

Why quarterly tax estimates matter

Setting aside money as you earn it can help you avoid a large surprise when you file. A payment plan also helps you make business decisions with a clearer view of what is available for expenses, hiring, equipment or owner draws.

The calculator estimates a safe-harbor amount using the smaller of 90% of this year's estimated tax or 100% of last year's tax. The prior-year target is 110% if last year's adjusted gross income was over $150,000. These targets include withholding as well as estimated payments. Meeting a target may help you avoid an underpayment penalty, but it does not necessarily cover your full tax bill.

How to use this quarterly estimated tax calculator

1. Enter your expected business profit for 2026. Use profit after business expenses, not gross sales.
2. Add W-2 wages and other taxable income if you expect them. Include federal tax withheld from wages so the estimate can account for what you have already paid.
3. Choose your filing status. The calculator uses the corresponding federal income-tax brackets and standard deduction in its estimate.
4. If you have it, enter last year's total federal tax. The calculator uses that figure to compare the prior-year safe-harbor amount with the current-year estimate.
5. Review the estimated payment and the breakdown. The result is an estimate based on the information entered, not a replacement for preparing your tax return.

Quarterly estimated tax example

How to read your estimated tax results

Start with the estimated payment each quarter. It is the calculator's suggested installment after accounting for withholding and the safe-harbor target. The 2026 estimated payment due dates are April 15, June 15 and September 15, 2026, and January 15, 2027.

The tax breakdown shows how the estimate is built. The calculator subtracts half of self-employment tax and the standard deduction before estimating taxable income. It also estimates a qualified business income deduction using the method stated with the calculator. Your eligibility and deduction may differ, so treat this as an estimate rather than a final tax calculation.

How to make your tax estimate more useful

1. 01

   Update your profit estimate

   Revise expected profit when sales, expenses or contracts change. If a client delays payment or you take on a new project, update the estimate instead of relying on an old forecast.

2. 02

   Track withholding and payments

   Keep your pay stubs and records of estimated payments together. Enter the federal tax withheld from wages and any prior-year tax accurately so you can compare the estimate with what you have already paid.

3. 03

   Separate tax cash from operating cash

   Consider moving money set aside for taxes into a separate account. This can help you avoid spending funds you expect to owe while planning purchases, payroll or owner draws.

4. 04

   Check the inputs against your records

   Review business profit, filing status and other income before acting on the result. Tax rules and your personal circumstances can affect the final amount. Confirm your estimate with a qualified tax professional.

Common quarterly tax estimate mistakes

• Entering revenue instead of profit

  Business profit is after business expenses. Using gross sales can make your estimated tax higher than it should be.

• Forgetting wage withholding

  If you or your spouse has wages, include the federal tax withheld. Leaving it out can overstate what still needs to be paid through estimates.

• Treating the safe-harbor target as the full bill

  The target helps you assess penalty exposure. You may still owe more when you file if your final tax is higher than the amount paid during the year.

• Assuming the deduction estimate fits every business

  The calculator uses a simplified estimate for the qualified business income deduction. Eligibility and limits depend on tax details that may not be captured by the inputs.

The quarterly estimated tax formula

Key terms

Estimated tax

A payment made during the year toward tax you expect to owe, including tax on income that does not have enough withholding.

Safe harbor

A payment target based on a portion of this year's estimated tax or last year's total tax, used to assess underpayment-penalty risk.

Self-employment tax

The tax the calculator estimates on business income to account for Social Security and Medicare taxes.

Qualified business income deduction

A deduction the calculator estimates from eligible business income, subject to tax rules and limits.

Marginal income-tax rate

The rate applied to the next portion of taxable income under the applicable federal tax brackets.