Q3 Estimated Tax Deadline 2026

If you're self-employed, a business owner, or have significant income without tax withholding, your Q3 2026 estimated tax payment is due September 15, 2026. Here's who needs to pay, how to figure out the right amount, and what happens if you're late.

Estimated taxes aren't optional for most business owners. The IRS expects tax to be paid as you earn income throughout the year, not all at once in April. Missing a quarterly deadline, or paying too little, can trigger penalties even if you pay your full balance on time when you file.

Who Needs to Make a Q3 Payment?

You generally need to make estimated payments if you expect to owe at least $1,000 in tax for the year after subtracting withholding and credits, and you're a sole proprietor, partner, S-corp shareholder, or otherwise receive income without tax withheld from it. If your only income is a W-2 job with proper withholding, you likely don't need to file these.

How to Calculate Your Q3 Payment

Safe harbor method: Pay 25% of last year's total tax liability per quarter (110% if your prior-year adjusted gross income was over $150,000). This protects you from underpayment penalties regardless of how this year actually performs.

Actual income method: Estimate this year's income through Q3, calculate the tax owed, and pay accordingly. This works better if your income is meaningfully different from last year, but it requires more accurate bookkeeping to get right.

What Happens If You Miss the Deadline

The IRS charges an underpayment penalty calculated quarterly, based on the current federal short-term rate plus 3%. Paying late for Q3 and catching up in Q4 doesn't erase the penalty for the quarter you missed. If you've fallen behind, the best move is to pay what you can now and catch up your withholding or next payment, rather than waiting until the full amount is available.

How to Make the Payment

Estimated payments can be made online through IRS Direct Pay, the Electronic Federal Tax Payment System (EFTPS), or by mailing Form 1040-ES with a check. Colorado also requires a separate estimated payment if you owe state tax; check the Colorado Department of Revenue's Revenue Online system for that deadline, which typically aligns with the federal date.

Not sure what you owe for Q3?

Latitude Tax Advisors can calculate your exact Q3 payment based on your actual year-to-date numbers, not just a guess, so you're not overpaying or risking a penalty.

Get Your Q3 Number Calculated

Frequently Asked Questions

When is the Q3 2026 estimated tax deadline?

September 15, 2026. This applies to calendar-year filers making their third of four estimated tax payments for the year.

What happens if I don't pay estimated taxes at all?

You'll owe the full tax balance when you file, plus an underpayment penalty calculated for each quarter you should have paid but didn't. The penalty is based on how much was owed and how late it was.

Can I skip a quarter if I had a slow period?

Yes, if you use the "actual income" calculation method rather than the safe harbor method, your payment for a slow quarter can reasonably be lower. This requires Form 2210 Schedule AI to document the uneven income if you're audited on it.

Do S-corp owners need to make estimated payments?

S-corp owners typically handle tax two ways: through payroll withholding on their W-2 wages, and through estimated payments on their share of the business's pass-through income. Both may need adjusting mid-year if the business's profit changes.