The majority of deadlines listed here are for Tax Year 2023. Some apply to upcoming Tax Years and some are IRS or Federal deadlines.
Prepare, eFile, Download
CT + IRS Tax Return
April 15, 2024
Tax Year 2023
Income Tax Return
Prepare and e-File an IRS (Due Date April 15, 2024) and Connecticut State Income Tax Return (Due Date April 15, 2024) until October 15, 2024. -
eFileIT
April 15, 2024
2023 Income Tax Extension
October 15, 2024
Tax Year 2023
Income Tax Return after the April 15, 2024 Connecticut Tax Extension
Last day to e-File a 2023 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, 2024 via mail-in Forms.
Forms incl. Mailing Address are listed below.
Tax Year 2023
Income Tax Return after the April 15, 2024 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, 2024. (Optionally, the
eFileIT deadline is Oct. 15, 2024). 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
2023, 2024, etc.
Other State Tax Return, Extension, Amendment Deadlines
2023, 2024, etc.
IRS Federal Income Tax Return, Amendment, Extension Deadlines
April 15, 2025
2021 Connecticut Income Tax Return Refund
The last day to file and claim your 2021 Connecticut Income Tax Return. This deadline does not apply if you owe Income Taxes.After that date your 2021 tax refund will expire.
Details.
April 15, 2026
2022 Connecticut Income Tax Return Refund
The last day to file and claim your 2022 Connecticut Income Tax Return. This deadline does not apply if you owe Income Taxes. After that date your 2022 tax refund will expire.
Details.
April 15, 2027
2023 Connecticut Income Tax Return Refund
The last day to file and claim your 2023 Connecticut Income Tax Return. This deadline does not apply if you owe Income Taxes. After that date your 2023 tax refund will expire.
Details.