How to pay Connecticut estimated taxes.

Do you need to pay?

You must make estimated payments if your Connecticut income tax, after withholding and any Pass-Through Entity Tax Credit, is $1,000 or more, and you expect withholding plus that credit to be less than your required annual payment.

Your required annual payment is the lesser of 90% of the tax on your 2026 return or 100% of the tax on your 2025 return (if that return covered 12 months). There is no 110% high-income rule. Nonresidents and part-year residents who had no Connecticut-sourced income in 2025 must use 90% of 2026 tax.

If you underpay: Interest of 1% per month or fraction of a month on each underpaid installment, until the earlier of April 15, 2027 or the date paid.

For how to pick a safe amount, see how much to pay in estimated taxes.

Deadlines

Four installments of 25% each due April 15, June 15, and September 15, 2026, and January 15, 2027. This matches the federal schedule.

A date on a weekend or holiday moves to the next business day. Pay at least two business days early.

Paying Connecticut, step by step

What you need

• Nothing to set up. myconneCT takes payments without an account.
• Your Social Security number and a copy of last year's Connecticut return.
• Your bank routing and account numbers.

Start at myconneCT, Connecticut's official payment site.

1. Go to the myconneCT home page. You do not need to log in.
2. In the Individuals panel, click Make a Payment or Estimated Payment.
3. Choose the estimated payment option and enter your identifying information.
4. Enter the amount and payment date, and select Direct Payment to pay from your bank account.
5. Enter the payer's name and email, click Submit, and keep the confirmation number.

Other ways to pay: ACH debit (Direct Payment) is free and can be scheduled up to 45 days ahead. Credit or debit card payments go through ACI Payments at acipayonline.com for a convenience fee (rate not published by DRS) and cannot be future-dated; do not mail the coupon if you pay by card. You can also mail a check payable to Commissioner of Revenue Services with the CT-1040ES coupon to DRS, PO Box 2932, Hartford CT 06104-2932, writing '2026 Form CT-1040ES' on the check.

Extension payments

File Form CT-1040 EXT by April 15 for a six-month extension to October 15. You do not need to file it if you got a federal extension and expect to owe no more Connecticut tax. It does not extend the time to pay; to request more time to pay, file Form CT-1127. File and pay the extension in myconneCT, by card, or by mailing the form with a check.

Make this year's first estimated payment as a separate transaction, marked as an estimate for the current year.

Good to know

• Any Pass-Through Entity Tax Credit from your business's Schedule CT K-1 counts toward your required payments, so factor it in before sizing estimates.
• If you file your 2026 return and pay in full by January 31, 2027, you are not charged interest for skipping the January 15 payment.
• If you mail a coupon, DRS mails you preprinted coupons for the remaining quarters.
• Moved this year? You may owe estimates to both Connecticut and your other state for the part of the year you lived or earned income in each.
• Paying the IRS too? Follow the federal walkthrough. Other states each have a guide of their own.

Official sources

Checked October 2026 against the Connecticut Department of Revenue Services's own publications.

• 2026 Form CT-1040ES (Rev. 01/26)
• myconneCT Information for Individuals (DRS-146)
• Making a Bill Payment (Non-logged In) tutorial
• 2025 Form CT-1040 EXT

This guide is for general education and reflects rules as of October 2026. Tax law and agency websites change, and your situation may have details that change the answer. Please talk with your tax professional before acting on it.