Connecticut Business Tax Extension LLC / Partnership – S Corporation – C Corporation – Fiduciary / Estate / Trust
Connect with a U.S.-based CPA or Enrolled Agent to prepare and file your Connecticut business return. Upfront pricing, secure document upload, no surprises.
Connect with a TaxPro →Connecticut Business Tax Extension – LLC / Partnership
Form CT-1065/CT-1120SI EXT • LLC / PartnershipConnecticut LLC & Partnership Tax Extension
Connecticut LLCs and partnerships file their returns with the Connecticut Department of Revenue Services. Connecticut mirrors the federal extension schedule–once your IRS Form 7004 is approved, the state automatically grants a corresponding 6-month filing extension with no additional paperwork required.
How the Extension Works
File IRS Form 7004 before March 16, 2026 (the March 15 original deadline shifts one day because it falls on a Sunday in 2026). Connecticut automatically recognizes an approved federal extension–no separate state form is required. Submit any Connecticut tax owed using Form CT-1065/CT-1120SI EXT or pay online by the original due date. File your completed Connecticut LLC or partnership return by September 15, 2026.
Best Practices
- File IRS Form 7004 before March 16, 2026 to activate your automatic Connecticut extension–no separate state form needed.
- Remit any Connecticut LLC or partnership tax with Form CT-1065/CT-1120SI EXT by March 16, 2026.
- Use the Connecticut DRS online portal for immediate electronic payment confirmation.
- File your completed Connecticut LLC or partnership return by September 15, 2026.
Working with a Tax Professional
LLC / Partnership returns carry unique complexities – a licensed CPA or Enrolled Agent can navigate the details and ensure your Connecticut return is filed accurately and on time.
- Get matched with a verified U.S.-based CPA or Enrolled Agent
- Upload your business documents via secure drag-and-drop
- Review your return with transparent, upfront pricing
- Your TaxPro files the Connecticut return by September 15, 2026
How to Pay
Connecticut requires online payment for tax amounts of $750 or more. Submit electronically via the Connecticut Online Tax Extension Payment portal. For amounts under $750, complete Form CT-1065/CT-1120SI EXT and mail with your payment.
Connecticut Online Payment Portal
Submit electronically through the Connecticut Online Tax Extension Payment system. Required for all payments $750 and above.
Form CT-1065/CT-1120SI EXT by Check
Download Form CT-1065/CT-1120SI EXT and mail with your check or money order. Include your EIN and tax year on the check.
P.O. Box 2934
Hartford, CT 06104-2934
Late Filing & Payment Penalties
| Penalty Type | Amount |
|---|---|
| Failure to File | $50 or 10% of the tax due, whichever is greater |
| Failure to Pay | $50 or 10% of the tax due, whichever is greater |
LLC / Partnership Quick Reference
| State Abbreviation | CT |
| Entity Type | LLC / Partnership |
| Extension Status | Automatic with approved IRS Form 7004 |
| Original Filing Deadline | March 16, 2026 |
| Extended Filing Deadline | September 15, 2026 |
| Payment Due | March 16, 2026 (100% of tax owed) |
| Payment Form | Form CT-1065/CT-1120SI EXT |
| Online Payment | Connecticut Online Tax Extension Payment |
| State Agency | Connecticut Department of Revenue Services |
| Failure to File Penalty | $50 or 10% of the tax due, whichever is greater |
| Failure to Pay Penalty | $50 or 10% of the tax due, whichever is greater |
Connecticut Business Tax Extension – S Corporation
Form CT-1065/CT-1120SI EXT • S CorporationConnecticut S Corporation Tax Extension
Connecticut S corporations file with the Connecticut Department of Revenue Services. Connecticut piggybacks on the federal extension process–an approved IRS Form 7004 automatically extends your Connecticut S corporation filing deadline by 6 months, with no separate state application needed.
How the Extension Works
Connecticut S corporations share the same extension process as partnerships–file IRS Form 7004 before March 16, 2026 and Connecticut automatically honors the extension. Note that March 15 falls on a Sunday in 2026, shifting the original due date to March 16. Use Form CT-1065/CT-1120SI EXT to submit any payment due, then file the completed return by September 15, 2026.
Best Practices
- Secure your federal extension by filing IRS Form 7004 before March 16, 2026–Connecticut’s state extension follows automatically.
- Pay any S corporation tax due with Form CT-1065/CT-1120SI EXT by March 16, 2026.
- Make payments electronically through the Connecticut DRS online portal for same-day processing.
- Submit your completed Connecticut S corporation return by September 15, 2026.
Working with a Tax Professional
S Corporation returns carry unique complexities – a licensed CPA or Enrolled Agent can navigate the details and ensure your Connecticut return is filed accurately and on time.
- Get matched with a verified U.S.-based CPA or Enrolled Agent
- Upload your business documents via secure drag-and-drop
- Review your return with transparent, upfront pricing
- Your TaxPro files the Connecticut return by September 15, 2026
How to Pay
Connecticut requires online payment for tax amounts of $750 or more. Submit electronically via the Connecticut Online Tax Extension Payment portal. For amounts under $750, complete Form CT-1065/CT-1120SI EXT and mail with your payment.
Connecticut Online Payment Portal
Submit electronically through the Connecticut Online Tax Extension Payment system. Required for all payments $750 and above.
Form CT-1065/CT-1120SI EXT by Check
Download Form CT-1065/CT-1120SI EXT and mail with your check or money order. Include your EIN and tax year on the check.
P.O. Box 2934
Hartford, CT 06104-2934
Late Filing & Payment Penalties
| Penalty Type | Amount |
|---|---|
| Failure to File | $50 or 10% of the tax due, whichever is greater |
| Failure to Pay | $50 or 10% of the tax due, whichever is greater |
S Corporation Quick Reference
| State Abbreviation | CT |
| Entity Type | S Corporation |
| Extension Status | Automatic with approved IRS Form 7004 |
| Original Filing Deadline | March 16, 2026 |
| Extended Filing Deadline | September 15, 2026 |
| Payment Due | March 16, 2026 (100% of tax owed) |
| Payment Form | Form CT-1065/CT-1120SI EXT |
| Online Payment | Connecticut Online Tax Extension Payment |
| State Agency | Connecticut Department of Revenue Services |
| Failure to File Penalty | $50 or 10% of the tax due, whichever is greater |
| Failure to Pay Penalty | $50 or 10% of the tax due, whichever is greater |
Connecticut Business Tax Extension – C Corporation
Form CT-1065/CT-1120SI EXT • C CorporationConnecticut C Corporation Tax Extension
Connecticut C corporations are subject to the Connecticut corporate income tax, administered by the Connecticut Department of Revenue Services. Connecticut grants C corporations a 7-month filing extension when a valid federal IRS Form 7004 extension is in place–moving the deadline from April 15 all the way to November 15, 2026.
How the Extension Works
Connecticut C corporations that obtain a federal extension from the IRS automatically receive a corresponding state extension. Use Form CT-1120EXT to remit any Connecticut corporate tax owed by April 15, 2026. Mail payments to: Department of Revenue State of Connecticut, P.O. Box 2934, Hartford, CT 06104-2934, or pay online at the Connecticut DRS portal. Note that Connecticut grants C corporations a 7-month extension–one month longer than the 6-month extension given to pass-through entities.
Best Practices
- File IRS Form 7004 before April 15, 2026 to activate Connecticut’s automatic C corporation extension to November 15, 2026.
- Remit Connecticut corporate tax owed with Form CT-1120EXT by April 15, 2026.
- Pay electronically at the Connecticut DRS payment portal to avoid mailing delays and get a confirmed receipt.
- File your completed Connecticut C corporation return by November 15, 2026.
Working with a Tax Professional
C Corporation returns carry unique complexities – a licensed CPA or Enrolled Agent can navigate the details and ensure your Connecticut return is filed accurately and on time.
- Get matched with a verified U.S.-based CPA or Enrolled Agent
- Upload your business documents via secure drag-and-drop
- Review your return with transparent, upfront pricing
- Your TaxPro files the Connecticut return by November 15, 2026
How to Pay
Connecticut requires online payment for tax amounts of $750 or more. Submit electronically via the Connecticut Online Tax Extension Payment portal. For amounts under $750, complete Form CT-1065/CT-1120SI EXT and mail with your payment.
Connecticut Online Payment Portal
Submit electronically through the Connecticut Online Tax Extension Payment system. Required for all payments $750 and above.
Form CT-1065/CT-1120SI EXT by Check
Download Form CT-1065/CT-1120SI EXT and mail with your check or money order. Include your EIN and tax year on the check.
P.O. Box 2934
Hartford, CT 06104-2934
Late Filing & Payment Penalties
| Penalty Type | Amount |
|---|---|
| Failure to File | $50 or 10% of the tax due, whichever is greater |
| Failure to Pay | $50 or 10% of the tax due, whichever is greater |
C Corporation Quick Reference
| State Abbreviation | CT |
| Entity Type | C Corporation |
| Extension Status | Automatic with approved IRS Form 7004 |
| Original Filing Deadline | April 15, 2026 |
| Extended Filing Deadline | November 15, 2026 |
| Payment Due | April 15, 2026 (100% of tax owed) |
| Payment Form | Form CT-1065/CT-1120SI EXT |
| Online Payment | Connecticut Online Tax Extension Payment |
| State Agency | Connecticut Department of Revenue Services |
| Failure to File Penalty | $50 or 10% of the tax due, whichever is greater |
| Failure to Pay Penalty | $50 or 10% of the tax due, whichever is greater |
Connecticut Business Tax Extension – Fiduciary / Estate / Trust
Form CT-1065/CT-1120SI EXT • Fiduciary / Estate / TrustConnecticut Fiduciary Tax Extension
Connecticut estates and trusts file fiduciary income tax returns with the Connecticut Department of Revenue Services. Connecticut honors the federal extension schedule–an approved IRS Form 8868 extension automatically extends the Connecticut fiduciary return deadline to September 30, 2026, with no separate state filing required.
How the Extension Works
File IRS Form 8868 with the IRS before April 15, 2026. Once the federal extension is approved, Connecticut automatically extends the fiduciary return filing deadline to September 30, 2026. If tax is owed, pay using the Application for Extension of Time to File Connecticut Income Tax Return for Trusts and Estates or through the Connecticut DRS online portal by April 15, 2026.
Best Practices
- File IRS Form 8868 before April 15, 2026 to secure your automatic Connecticut fiduciary extension to September 30, 2026.
- Remit all Connecticut fiduciary income tax owed by April 15, 2026 using the CT-1041 extension payment form.
- Pay electronically through the Connecticut DRS payment portal for a timestamped confirmation.
- File your completed Connecticut fiduciary return (Form CT-1041) by September 30, 2026.
Working with a Tax Professional
Fiduciary / Estate / Trust returns carry unique complexities – a licensed CPA or Enrolled Agent can navigate the details and ensure your Connecticut return is filed accurately and on time.
- Get matched with a verified U.S.-based CPA or Enrolled Agent
- Upload your business documents via secure drag-and-drop
- Review your return with transparent, upfront pricing
- Your TaxPro files the Connecticut return by September 30, 2026
How to Pay
Connecticut requires online payment for tax amounts of $750 or more. Submit electronically via the Connecticut Online Tax Extension Payment portal. For amounts under $750, complete Form CT-1065/CT-1120SI EXT and mail with your payment.
Connecticut Online Payment Portal
Submit electronically through the Connecticut Online Tax Extension Payment system. Required for all payments $750 and above.
Form CT-1065/CT-1120SI EXT by Check
Download Form CT-1065/CT-1120SI EXT and mail with your check or money order. Include your EIN and tax year on the check.
P.O. Box 2934
Hartford, CT 06104-2934
Late Filing & Payment Penalties
| Penalty Type | Amount |
|---|---|
| Failure to File | $50 or 10% of the tax due, whichever is greater |
| Failure to Pay | $50 or 10% of the tax due, whichever is greater |
Fiduciary / Estate / Trust Quick Reference
| State Abbreviation | CT |
| Entity Type | Fiduciary / Estate / Trust |
| Extension Status | Automatic with approved IRS Form 7004 |
| Original Filing Deadline | April 15, 2026 |
| Extended Filing Deadline | September 30, 2026 |
| Payment Due | April 15, 2026 (100% of tax owed) |
| Payment Form | Form CT-1065/CT-1120SI EXT |
| Online Payment | Connecticut Online Tax Extension Payment |
| State Agency | Connecticut Department of Revenue Services |
| Failure to File Penalty | $50 or 10% of the tax due, whichever is greater |
| Failure to Pay Penalty | $50 or 10% of the tax due, whichever is greater |
Extended? Your Connecticut Business Return Deadline Is Coming Up.
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