Where is My Refund?   |   October 15 Deadline   |   Why eFile?

Connecticut Income Taxes and CT State Tax Forms

Connecticut State Income Taxes for Tax Year 2020  (January 1 - Dec. 31, 2020) can be prepared and e-Filed now along with an IRS or Federal Income Tax Return (or you can learn how to only prepare and file a CT state return).The Connecticut tax filing and tax payment deadline is April 15, 2021 May 17, 2021. Find IRS or Federal Tax Return deadline details.

efile Connecticut tax return
"The Constitution State"

eFile.com makes it easy for you to e-file your IRS and Connecticut State Tax Return (e.g resident, nonresident, or part-year resident returns). However, the IRS and the respective State Tax Agencies require you to e-file a Federal Income Tax Return at the same time you e-file a State Tax Return. This is not an eFile.com policy but an IRS and State Agency policy. Thus, technically you cannot e-File anywhere - not just eFile.com - a Connecticut Tax Return without also e-filing the associated IRS Tax Return. But there is good news, please read on.

Detailed instructions on how you can only prepare and mail in - not eFile - a Connecticut 2020 Tax Return - here via eFile.com. However, you must download/print and sign the forms and mail them to the Tax Agency.

Prepare only a CT State Return without an IRS return. Details
Step by Step instructions on how to only Prepare and Download - not eFile - State Returns on eFile.com.
Where Is Your Connecticut Tax Refund Money
Step 1: Sign into your eFile.com account and check acceptance by the Tax Agency.
Step 2: Check your Connecticut Tax Refund Status.
Where is Your IRS Refund?
Step 1: Sign into your eFile.com account and check acceptance by the IRS.
Step 2: Check your IRS Tax Refund Status.
Connecticut Income Tax Extension
How to correct a rejected Tax Return
If your CT Tax Return was rejected by the CT Tax Agency - not eFile.com - instructions on how to correct a rejected Connecticut Tax Return.
How to Pay Income Taxes
Connecticut, IRS Late Filing, Tax Payment Penalties
1. Outstanding Tax Balance after Original Deadline: 10% penalty and 1% interest rate for each month or fraction of a month until payment is made.
4. IRS Penalties: Calculate and Estimate your potential IRS Income Tax Return Penalties.
CT Tax Return Mailing Addresses
Find various Connecticut Mailing Addresses for tax returns, tax amendments, and tax payments. 
Connecticut Income Tax Brackets
Connecticut Income Tax Forms
Connecticut Unemployment Benefits
Unemployment benefits is taxed to the same extent as federal law in Connecticut.


Start Federal and Connecticut Tax Returns


2021 Connecticut Income Tax Filing Deadlines by Tax Year

The majority of deadlines listed here are for Tax Year 2020. Some apply to upcoming Tax Years and some are IRS or Federal deadlines.

May 17, 2021
Tax Year 2020
Income Tax Return
Prepare and e-File an IRS (Due Date May 17, 2021) and Connecticut State Income Tax Return (Due Date May 17, 2021) until October 15, 2021. - eFileIT*
May 17, 2021
2020 Income Tax Extension
October 15, 2021
Tax Year 2020
Income Tax Return after the May 17, 2021 Connecticut Tax Extension
Last day to e-File a 2020 Connecticut State Income Tax Return for Tax Extension Filers and late eFilers. You can only e-File (to file by paper see below) Connecticut Income Tax Return together with an IRS Tax Return. eFileIT*
October 15, 2021 via mail-in Forms.
Forms incl. Mailing Address are listed below.
Tax Year 2020
Income Tax Return after the May 17, 2021 Connecticut Tax Extension
Deadline for taxpayers who got an CT Tax Extension to file their Connecticut Income Tax Return by mail-in Forms - the Forms incl. mailing addresses are listed below - is Oct. 15, 2021. (Optionally, the eFileIT* deadline is Oct. 15, 2021). Instructions on how to only - without the IRS return - prepare and file a Connecticut State Income Tax Return on eFile.com.
Tax Amendment for all Tax Years
IRS Due Dates
IRS Tax Return, Extension, Amendment Deadlines
2021, 2022, etc.
Other State Tax Return, Extension, Amendment Deadlines
Select respective State Tax Return Deadlines.
2021, 2022, etc.
IRS Federal Income Tax Return, Amendment, Extension Deadlines
May 17, 2024
2020 Connecticut Income Tax Return Refund.
IRS Tax Return Refund Claim Deadline
The last day to file - you will not face late filing penalties - and claim your 2020 Connecticut Income Tax Return Refund. This deadline does not apply if you owe 2020 Income Taxes.

E-File These 2020 Connecticut State Tax Forms

Prepare and e-File these state forms for 2020 in conjunction with your Federal and State Income Tax Return. As you proceed through the tax interview on eFile.com, the application will select the correct state forms for you. You can also select tax forms individually. All these forms will then be e-filed by you to the State Tax Agency. Instructions on how to only prepare a state income tax return.

eFileIT Now*
Form CT-1040
Resident Income Tax Return
Form CT-1040ES
Estimated Connecticut Income Tax Payment Coupon for Individuals
Form CT-1040NR/PY
Nonresident/Part-Year Resident Tax Return
Form CT-2210
Underpayment of Estimated Income Tax by Individuals, Trusts, and Estates
Form CT-6251
Alternative Minimum Tax Return
Form CT-8822
Change of Address
Form CT-8857
Request for Innocent Spouse Relief
Form OP-186
Connecticut Individual Use Tax Return
Schedule CT-1040WH
Connecticut Income Tax Withholding Supplemental Schedule
Schedule CT-EITC
Connecticut Earned Income Tax Credit
Determines your paycheck CT Tax Withholding amount per employer.
Step 1: Complete and submit to your employer(s).
Step 2: Estimate, Calculate your IRS Tax Withholding now.
Payment Voucher for Individual e-filed Returns. Complete and submit to the CT Department of Revenue - address is on the form - with your payment.

* Due to IRS and State Tax Agency tax data sharing and validation requirements, you can only e-file a State Income Tax Return while also e-filing a Federal Income Tax Return. This is not an eFile.com created policy, but all online tax web sites have to adhere to this IRS/state issued tax data sharing policy. You can however prepare all 44 State Income Tax Returns on eFile.com if you have already e-Filed or filed your IRS return. Instructions on how you can ONLY prepare and file State Income Tax Return(s). Only on eFile.com can you prepare, file or e-file unlimited State Tax Returns for one low price and not pay for each State return like you would do on H&R Block® vs. TurboTax®. Dare to Compare Now.

Connecticut Income Tax Extension

For Tax Year 2020, if you do not expect to owe CT Taxes, you do not need to file an extension.  However, if you owe CT Taxes and unsure if you can file on time, then e-File an IRS Tax Extension by April 15, 2021 May 17, 2021 for free on eFile.com (instructions on whether you should consider a Tax Extension or not).  You can file and pay Form CT-1040 EXT electronically at CT TSC-IND (Note: The Extension Deadline has passed for Tax Year 2019 and will reopen for Tax Year 2020).  The extended e-File deadline is Oct. 15, 2021 and the Connecticut paper filing due date is October 15, 2021.   Keep in mind however, a Connecticut or IRS tax extension does not extend the due date to pay owed taxes or income tax liabilities penalty free.

If you owe Connecticut and/or IRS income taxes and don't pay them by Tax Day, you will be charged Connecticut and IRS late tax payment penalties. Calculate and estimate IRS late payment penalties. If you expect to owe taxes, and you want to pay by check/money order, you should still pay what you owe and mail Form CT-1040 EXT along with your payment - before May 17, 2021.

The extended IRS/Connecticut eFile deadline is Oct. 15, 2021 - eFileIT* now. If you plan to file or mail-in a Connecticut tax return on paper - the Mailing Address are below - your due date is October 15, 2021.

Connecticut State Tax Payment Options
You can select one of these payment options either after you have e-filed or filed your 2020 Connecticut Tax Return. Alternatively, you can pay Connecticut income taxes here prior to filing (e.g in the case of an extension). Plus, you can make online Connecticut tax estimate payments for next tax year. If you eFiled your taxes and pay online, you do not have to send in Connecticut paper forms (e.g. payer tax return, extension form, or tax estimate form). 
Go to the Connecticut TSC site to submit your payment. Make sure you select "Make a Bill Payment" if you filed your CT return electronically, received a bill, or filed by mail.
This is a free option if you want to pay your taxes owed via your bank account.
Submit a tax payment through the state tax agency's Official Payments site. When you're on the site, select the "Individual Income Tax (Current Year Taxes)" option, then follow the on-screen prompts to enter and submit your information.
Use this payment option if you want to pay your tax payment via your credit or debit card. There is an additional convenience fee added based on your total payment when you submit with your card.
Check or Money Order with Form CT-1040V
Complete voucher Form CT-1040V and attach it to your check or money order payable to "Commissioner of Revenue Services". Write your Social Security number and "2019 CT-1040V e-file" on the check. Mail them to the Form CT-1040V address below.
Use this payment option if you wish to submit your payment via check or money order in the mail. 
Estimated Tax Payment Options
Choose one of these options: 1) Go to the Connecticut TSC site to submit your estimated payment.  Pay via ACH credit by sending tax payments from your bank account to Connecticut Department of Revenue Services bank account.  2) Pay via credit or debit card through Official Payments (choose the "Estimated Taxes" as your Payment Type). Be aware that a convenience fee based on your total amount when you submit with your card. 4) Complete voucher Form CT-1040ES. Attach a check or money order for the tax period payable to "Commissioner of Revenue Services". Write your Social Security numbers and "2021 Form CT-1040ES" on the check or money order. Mail the voucher and check/money order to the Form CT-1040ES address here.
Use one of these payment options if you want to submit estimated taxes rather than submit all your taxes owed at once. 
Many of these online IRS tax payment options can be used before or after you e-Filed your Income Taxes. You can pay tax extension and tax estimate payments. For estimate payments, you do not have to submit a form. Extension you can eFile on eFile.com for free.
These payment options are independent from you preparing and eFiling your tax returns on eFile.com. eFile.com offers these payment options for the convenience of all tax payers.


Connecticut Tax Return, Amendment, etc. Mailing Addresses
Addresses to mail Connecticut Tax Returns, Amendments, Extensions, or Tax Payments.
CT Tax Return or Amended Tax Return: Address if you expect a Tax Refund on your Tax Return
Department of Revenue Services
State of Connecticut
P.O. Box 2976
Hartford CT 06104-2976
CT Tax Return or Amended Return: Address if you owe Taxes and include payment.
Department of Revenue Services
State of Connecticut
P.O. Box 2977
Hartford CT 06104-2977
CT Tax Extension: Address if you owe Taxes and include payment. Tax Extension Payments, include Form CT-1040 EXT. Tip: Make Tax Payments online and you will not have to mail in Form CT-1040 EXT. See above.
Department of Revenue Services
State of Connecticut
P.O. Box 2977
Hartford CT 06104-2977
CT Tax Payment: include voucher Form CT-1040V
Department of Revenue Services
State of Connecticut
P.O. Box 2921
Hartford CT 06104-2921
CT Tax Estimate Payments: include Tax year 2021 Form CT-1040ES.
Department of Revenue Services
State of Connecticut
P.O. Box 2932
Hartford CT 06104-2932


Other U.S. States, Territories, and Protectorates.