Business owners

Quarterly Estimated Tax Calculator

Estimate a 2026 quarterly payment that may help you avoid an IRS underpayment penalty, based on your income, withholding and last year's tax.

Updated for the 2026 tax year

Estimates only. These calculators use simplified assumptions, 2026 federal and North Carolina rules and the numbers you enter. They don't account for every type of income, deduction, credit or circumstance, so your actual results may be different. They are for general information and are not tax, legal or investment advice. Using them doesn't create a CPA-client relationship with Stancil. Talk with a CPA about your own situation before acting on a result. The calculations run in your browser, and the calculator doesn't send the numbers you enter to Stancil.

Who needs to pay estimated taxes?

If tax isn't withheld from most of your income (self-employment, 1099 work, rentals, investments or a large bonus), the IRS expects you to pay during the year through quarterly estimated payments. You generally need to pay if you'll owe $1,000 or more when you file.

The safe-harbor rules

You generally won't owe an underpayment penalty if your withholding and on-time estimated payments add up to at least the smaller of:

  • 90% of this year's tax, or
  • 100% of last year's tax (110% if last year's AGI was over $150,000, or over $75,000 if you're married filing separately).

Each payment has to be on time

The IRS looks at each installment separately, not just the total for the year. In general, a quarter of the required amount is due by each due date. If an earlier payment was late or too small, paying extra later can reduce the penalty but may not remove it for that quarter. Withholding works differently: it's generally treated as paid evenly through the year.

Paying based on last year's tax is popular because it's a known number, even if your income goes up. If your income is uneven or your situation is more complex, a different approach may fit better.

2026 due dates

  • 1st quarter: April 15, 2026
  • 2nd quarter: June 15, 2026
  • 3rd quarter: September 15, 2026
  • 4th quarter: January 15, 2027

North Carolina estimated payments (Form NC-40) are due on the same dates.

Frequently asked questions

What happens if I miss a quarterly payment?

The IRS charges an underpayment penalty, which works like interest on the amount you were short for each day it was late. Paying as soon as you can reduces it. It isn't a reason to skip later payments.

Can I increase withholding instead of making estimated payments?

Yes. Withholding from a W-2 job (yours or your spouse's) is treated as paid evenly through the year, even if you increase it late in the year. That makes it a handy way to catch up.

What if my income is uneven during the year?

The annualized income installment method (Form 2210, Schedule AI) lets you pay less in early quarters if most of your income comes later. It takes more work to calculate, so it's worth asking your CPA.