CT-1040ES: Estimated Connecticut Income Tax Payment Coupon for Individuals (2025)

Who files this form

Use this coupon if you must make estimated Connecticut income tax payments for tax year 2025 and did not receive a preprinted coupon package from the Department of Revenue Services (DRS).

You must make estimated payments if both apply:

• Your Connecticut income tax, after subtracting Connecticut tax withheld and any allowable Pass-Through Entity Tax Credit (PE Tax Credit), is $1,000 or more.
• Your expected Connecticut withholding plus PE Tax Credit is less than your required annual payment for 2025.

Your required annual payment is generally the smaller of:

• 90% of the tax shown on your 2025 Connecticut income tax return; or
• 100% of the tax shown on your 2024 Connecticut income tax return, if that return covered 12 months.

You do not have to make estimated payments if you did not file a 2024 Connecticut return because you had no Connecticut income tax liability and you were either a Connecticut resident or a nonresident or part-year resident with Connecticut-sourced income in 2024.

If you were a nonresident or part-year resident with no Connecticut-sourced income in 2024, use 90% of your 2025 Connecticut tax as your required annual payment. Special rules apply to farmers and fishermen; the form refers them to Informational Publication 2021(2).

When it's due

The supplied form is marked DRAFT. It lists these estimated payment deadlines for tax year 2025:

• April 15, 2025
• June 15, 2025
• September 15, 2025
• January 15, 2026

If a due date falls on a Saturday, Sunday, or legal holiday, payment is timely if filed on the next business day. A mailed payment is timely if received or postmarked by the U.S. Postal Service on or before the due date. Fiscal-year filers should follow federal filing dates.

Other dates for tax year 2025:

• January 31, 2026: File your 2025 return and pay the amount due in full by this date to avoid interest for missing the January 15, 2026 estimated payment.
• March 1, 2026: A farmer or fisherman who files a 2025 Connecticut return and pays the amount due in full by this date will not be charged interest for underpayment of estimated tax.
• April 15, 2026: Pay your full 2025 tax liability with a timely filed return or an extension request to avoid possible late-payment penalties.

What you'll need

Have these forms and details available to complete the coupon and calculate your payment:

• Your name, Social Security number, and mailing address. Include your spouse’s name and Social Security number if married filing jointly.
• The payment due date and payment amount.
• The 2025 Estimated Connecticut Income Tax Worksheet on page 3 and its Tax Calculation Schedule.
• Your expected 2025 federal adjusted gross income, Connecticut modifications, Connecticut withholding, and allowable credits.
• Your 2024 Connecticut income tax return, if using the prior-year tax calculation, and the amount of any available 2024 overpayment.
• Your estimated PE Tax Credit, if applicable. The form says this credit is reported on Schedule CT K-1 or Schedule CT-1041 K-1.

If paying by mail, include the completed coupon and a signed check.

How to file

Online: File and pay Form CT-1040ES through myconneCT.

• ACH debit/direct payment lets DRS withdraw money from your checking or savings account on a date you select, up to the due date. There is no ACH debit fee.
• Credit or debit card payments have a convenience fee. You can cancel after being told the fee. Payment is effective on the date you make the charge.
• You will receive a confirmation number for your records. Do not mail Form CT-1040ES if you pay by credit or debit card.

By mail:

1. Complete the coupon in blue or black ink. Print all required identification information, the due date, and the payment amount.
2. Make your check payable to Commissioner of Revenue Services and sign it.
3. Write “2025 Form CT-1040ES” on the front of the check. Adding your Social Security number is optional.
4. Cut along the dotted line and paper clip the check to the front of the coupon. Do not use staples or send cash.
5. Mail the coupon and payment to:

Department of Revenue Services

PO Box 2932

Hartford CT 06104-2932

Common mistakes

• Using the wrong year’s coupon: DRS says each form is year-specific. Use the 2025 form for 2025 payments to avoid processing delays.
• Leaving out identification information: Complete all required fields, including your spouse’s Social Security number if married filing jointly.
• Putting the PE Tax Credit on worksheet Line 11: Do not include it there. Enter the estimated PE Tax Credit on Line 16a.
• Assuming a later payment removes earlier interest: Interest is calculated separately for each installment. You may owe interest even if you catch up later or receive a refund when you file.
• Mailing a coupon after paying by card: Do not mail Form CT-1040ES when paying by credit or debit card.
• Forgetting the income tax return after paying electronically: Electronic payment does not remove the requirement to file your return by its due date.

Questions people ask

Can I use my 2024 overpayment toward a 2025 installment?

Yes. You may subtract any available overpayment of 2024 income tax from your installment amount when entering the payment amount on the coupon.

How do I calculate my estimated payment?

Complete the 2025 Estimated Connecticut Income Tax Worksheet on page 3. It accounts for estimated tax, withholding, and the PE Tax Credit to determine whether a payment is required and calculate the installment amount.

What if my income changes throughout the year?

You may be able to reduce or eliminate a payment for one or more periods using the annualized income installment method. The form refers you to Informational Publication 2018(11) and Worksheet CT-1040 AES.

Will DRS send me coupons for later payments?

If you file this coupon, DRS will mail personalized, preprinted coupons for the remaining quarters of tax year 2025.

Official sources

• https://portal.ct.gov/-/media/drs/forms/2025/es-forms/ct1040es-flat0125.pdf