Connecticut business filing dates, 2027

State-level due dates for businesses filing in Connecticut. Every line links to the official page it came from, with the date that page was read. Where no official source has been verified, the line says so instead of showing a date.

Add to Google Calendar Add to Apple or Outlook Download .ics8 dated lines in the calendar file · sources last read 2026-09-23

Coverage · 2 of 6 fully dated

Income / franchise tax return1 date · 1 not dated yet
Estimated taxnot dated yet
Withholding1 date · 2 not dated yet
Unemployment insurance4 dates
Sales and use taxnot dated yet
Annual report1 date

Income / franchise tax return

1 date · 1 not dated yet

The annual return for the business’s tax year, and in franchise-tax states the report that keeps the entity in good standing. Which form and which date depend on the entity type and the tax year. Where the source grants an extension, it extends the time to file; the source says whether it also extends the time to pay.

Why no dates: Every date shown here is checked against its official source.

Obligation	Applies to	Due rule	2027 dates	Source · retrieved
Form CT-1120 Corporation Business Tax returncalendar-year C corporation Source text “Every corporation must file a return on or before the fifteenth day of the month following the due date of the corporation’s corresponding federal income tax return for the income year (May 15 for calendar year taxpayers). For example, if a corporation has a December 31st year end, the return is due on May 15th.”verbatim · portal.ct.gov · retrieved 2026-09-23 “Anything except June 30 \| 15th day of 5th month after year end \| 15th day of 11th month after year end”verbatim · portal.ct.gov · retrieved 2026-09-23 “Groups of companies with common ownership that are engaged in a unitary business, where at least one member of the group is subject to the Corporation Business Tax, are required to file Form CT-1120CU.”verbatim · portal.ct.gov · retrieved 2026-09-23 “C corporations that carry on or have the right to carry on business in Connecticut are required to file a Connecticut Corporation Business Tax Return.”verbatim · portal.ct.gov · retrieved 2026-09-23 “Requests that are granted will receive a six-month extension, except for those with a June 30th year end can receive a seven-month filing extension.”verbatim · portal.ct.gov · retrieved 2026-09-23 “Payment is not sufficient; you must timely file Form CT-1120 EXT, Application for Extension of Time to File Connecticut Corporation Business Tax Return, in order to receive an extension.”verbatim · portal.ct.gov · retrieved 2026-09-23	Applies toA C corporation that carries on, or has the right to carry on, business in Connecticut (the preparer attests) and files on its own (a member of a combined unitary group files Form CT-1120CU instead, not dated here) files by the 15th day of the month after its federal return is due: the 15th day of the 5th month after year-end (May 15 for calendar-year filers). An approved extension runs to the 15th day of the 11th month. June 30 year-ends have their own line. The source states no weekend rule, so the stated date is shown.	Due ruleCT-1120: 15th day of the 5th month after the tax year ends	2027 dates May 15SatCT-1120extended (CT-1120 EXT): Nov 15 Falls on a Saturday; the source states no weekend rule.	Source · retrievedportal.ct.gov/drs/corporation-tax/corp-faqs (official source, opens in a new tab)retrieved 2026-09-23
Form CT-1120 (June 30 year-end)	Applies toA C corporation that carries on, or has the right to carry on, business in Connecticut (the preparer attests) and files on its own (a member of a combined unitary group files Form CT-1120CU instead, not dated here) with a June 30 year-end files by October 15 (the 15th day of the 4th month after year-end); an approved extension runs to the 15th day of the 11th month. The source states no weekend rule, so the stated date is shown.	Due ruleUnsupported	2027 datesThe rule names no 2027 due date for any business it applies to.	Source · retrievedNo verified source on file

Form CT-1120 Corporation Business Tax returncalendar-year C corporation

Source text

“Every corporation must file a return on or before the fifteenth day of the month following the due date of the corporation’s corresponding federal income tax return for the income year (May 15 for calendar year taxpayers). For example, if a corporation has a December 31st year end, the return is due on May 15th.”verbatim · portal.ct.gov · retrieved 2026-09-23

“Anything except June 30 | 15th day of 5th month after year end | 15th day of 11th month after year end”verbatim · portal.ct.gov · retrieved 2026-09-23

“Groups of companies with common ownership that are engaged in a unitary business, where at least one member of the group is subject to the Corporation Business Tax, are required to file Form CT-1120CU.”verbatim · portal.ct.gov · retrieved 2026-09-23

“C corporations that carry on or have the right to carry on business in Connecticut are required to file a Connecticut Corporation Business Tax Return.”verbatim · portal.ct.gov · retrieved 2026-09-23

“Requests that are granted will receive a six-month extension, except for those with a June 30th year end can receive a seven-month filing extension.”verbatim · portal.ct.gov · retrieved 2026-09-23

“Payment is not sufficient; you must timely file Form CT-1120 EXT, Application for Extension of Time to File Connecticut Corporation Business Tax Return, in order to receive an extension.”verbatim · portal.ct.gov · retrieved 2026-09-23

Applies toA C corporation that carries on, or has the right to carry on, business in Connecticut (the preparer attests) and files on its own (a member of a combined unitary group files Form CT-1120CU instead, not dated here) files by the 15th day of the month after its federal return is due: the 15th day of the 5th month after year-end (May 15 for calendar-year filers). An approved extension runs to the 15th day of the 11th month. June 30 year-ends have their own line. The source states no weekend rule, so the stated date is shown.

Due ruleCT-1120: 15th day of the 5th month after the tax year ends

2027 dates

May 15SatCT-1120extended (CT-1120 EXT): Nov 15

Falls on a Saturday; the source states no weekend rule.

Source · retrievedportal.ct.gov/drs/corporation-tax/corp-faqsretrieved 2026-09-23

Form CT-1120 (June 30 year-end)

Applies toA C corporation that carries on, or has the right to carry on, business in Connecticut (the preparer attests) and files on its own (a member of a combined unitary group files Form CT-1120CU instead, not dated here) with a June 30 year-end files by October 15 (the 15th day of the 4th month after year-end); an approved extension runs to the 15th day of the 11th month. The source states no weekend rule, so the stated date is shown.

Due ruleUnsupported

2027 datesThe rule names no 2027 due date for any business it applies to.

Source · retrievedNo verified source on file

Estimated tax

Unsupported

Installments paid during the year toward the year’s tax. Whether a business must pay them depends on its expected liability, which this page cannot know; the lines show when installments fall due for those who must.

Why no dates: No official source confirmed yet for Connecticut's estimated tax payment due dates.

Obligation	Applies to	Due rule	2027 dates	Source · retrieved
Estimated tax	Applies toShown once verified	Due ruleUnsupported	2027 datesNo official source confirmed yet for Connecticut's estimated tax payment due dates.	Source · retrievedNo verified source on file

Withholding

1 date · 2 not dated yet

Returns and deposits of income tax withheld from employees’ wages. The agency assigns each employer a deposit frequency, usually from its past liability, so the dates differ by frequency.

Why no dates: Every date shown here is checked against its official source.

Obligation	Applies to	Due rule	2027 dates	Source · retrieved
Monthly withholding remittance Source text “Monthly Remitter You are a monthly remitter if your reported liability for Connecticut income tax withholding during the 12‑month look‑back period was more than $2,000 but not more than $10,000. As a monthly remitter, you are required to remit Connecticut income tax withholding on or before the fifteenth day of the month following the month during which the wages were paid.”verbatim · portal.ct.gov · retrieved 2026-09-23 “Monthly Remitter You are a monthly remitter if your reported liability for Connecticut income tax withholding during the 12‑month look‑back period was more than $2,000 but not more than $10,000. As a monthly remitter, you are required to remit Connecticut income tax withholding on or before the fifteenth day of the month following the month during which the wages were paid.”verbatim · portal.ct.gov · retrieved 2026-09-23	Applies toA monthly remitter (as the preparer declares the Connecticut classification) pays Connecticut withholding by the 15th of the month after the month the wages were paid. Covered for 2025 and 2026, the years whose employer guides (IP 2025(1), IP 2026(1)) state it. Quarterly and weekly remitter dates are not dated here. The source states no weekend rule, so the stated date is shown.	Due ruleMonthly withholding remittance: 15th day of the month after the month ends	2027 dates Jan 15FriMonthly withholding remittance	Source · retrievedportal.ct.gov/-/media/drs/publications/pubsip/2026/ip-2026-1.pdf (official source, opens in a new tab)retrieved 2026-09-23portal.ct.gov/-/media/drs/publications/pubsip/2025/ip-2025-1.pdf (official source, opens in a new tab)retrieved 2026-09-23
2025 withholding remitter classification	Applies toFor 2025, remitter status follows the look-back period liability: $2,000 or less quarterly; more than $2,000 up to $10,000 monthly; more than $10,000 weekly. DRS notifies employers of changes.	Due ruleUnsupported	2027 datesAuthority for 2027 not yet published; nothing is shown until it is.	Source · retrievedNo verified source on file
Monthly withholding remittance	Applies toA monthly remitter (as the preparer declares the Connecticut classification) pays Connecticut withholding by the 15th of the month after the month the wages were paid. Covered for 2025 and 2026, the years whose employer guides (IP 2025(1), IP 2026(1)) state it. Quarterly and weekly remitter dates are not dated here. The source states no weekend rule, so the stated date is shown.	Due ruleUnsupported	2027 datesAuthority for 2027 not yet published; no date is shown until it is.	Source · retrievedNo verified source on file

Unemployment insurance

4 dates

Employer contribution and wage reports for unemployment insurance: the state program, and FUTA at the federal level.

Obligation	Applies to	Due rule	2027 dates	Source · retrieved
Quarterly UI tax return Source text “1st Quarter returns and payments due on or before 4/30 2nd Quarter returns and payments due on or before 7/31 3rd Quarter returns and payments due on or before 10/31 4th Quarter returns and payments due on or before 1/31”verbatim · portal.ct.gov · retrieved 2026-09-23	Applies toAn employer the preparer lists as a quarterly Connecticut unemployment-insurance filer, and does not attest is a reimbursing employer: quarterly UI returns and payments are due April 30, July 31, October 31 and January 31. Reimbursing employers have 15 more days, not shown here. A Saturday, Sunday or holiday date moves to the next business day.	Due ruleQuarterly UI return: last day of the month after the quarter endsA date on a weekend moves to the next business day; state holidays are not compiled.	2027 dates Feb 1MonQuarterly UI return · moved from Sun Jan 31 Apr 30FriQuarterly UI return Aug 2MonQuarterly UI return · moved from Sat Jul 31 Nov 1MonQuarterly UI return · moved from Sun Oct 31 State legal holidays are not compiled: if this date is a state holiday, the deadline moves to the next business day.	Source · retrievedportal.ct.gov/dol/knowledge-base/articles/unemployment-taxes/what-are-the-due-dates-of-my-quarterly-tax-returns (official source, opens in a new tab)retrieved 2026-09-23

Quarterly UI tax return

Source text

“1st Quarter returns and payments due on or before 4/30 2nd Quarter returns and payments due on or before 7/31 3rd Quarter returns and payments due on or before 10/31 4th Quarter returns and payments due on or before 1/31”verbatim · portal.ct.gov · retrieved 2026-09-23

Applies toAn employer the preparer lists as a quarterly Connecticut unemployment-insurance filer, and does not attest is a reimbursing employer: quarterly UI returns and payments are due April 30, July 31, October 31 and January 31. Reimbursing employers have 15 more days, not shown here. A Saturday, Sunday or holiday date moves to the next business day.

Due ruleQuarterly UI return: last day of the month after the quarter endsA date on a weekend moves to the next business day; state holidays are not compiled.

2027 dates

Feb 1MonQuarterly UI return · moved from Sun Jan 31
Apr 30FriQuarterly UI return
Aug 2MonQuarterly UI return · moved from Sat Jul 31
Nov 1MonQuarterly UI return · moved from Sun Oct 31

State legal holidays are not compiled: if this date is a state holiday, the deadline moves to the next business day.

Source · retrievedportal.ct.gov/dol/knowledge-base/articles/unemployment-taxes/what-are-the-due-dates-of-my-quarterly-tax-returnsretrieved 2026-09-23

Sales and use tax

Unsupported

Returns for sales and use tax collected under a permit. The agency assigns each permit holder a filing frequency; the dates differ by frequency.

Why no dates: No official source confirmed yet for Connecticut's sales tax due dates.

Obligation	Applies to	Due rule	2027 dates	Source · retrieved
Sales and use tax	Applies toShown once verified	Due ruleUnsupported	2027 datesNo official source confirmed yet for Connecticut's sales tax due dates.	Source · retrievedNo verified source on file

Annual report

1 date

The annual or biennial report an entity files with the Secretary of State (or its equivalent) to stay in good standing. Some are keyed to the month the entity was formed.

Obligation	Applies to	Due rule	2027 dates	Source · retrieved
LLC annual reportsingle-member LLC or multi-member LLC Source text “The report is due each year between Jan. 1st and March 31st starting in 2018.”verbatim · portal.ct.gov · retrieved 2026-09-23	Applies toA limited liability company's annual report is due each year between January 1 and March 31.	Due ruleLLC annual report: March 31 of the year the calendar year ends	2027 dates Mar 31WedLLC annual report	Source · retrievedportal.ct.gov/-/media/SOTS/Business-Services/BSD-Forms/llc-2017/ANNUAL-REPORT-FREQUENTLY-ASKED-QUESTIONS.pdf (official source, opens in a new tab)retrieved 2026-09-23
Corporation organization and first report Source text “(The first report is due within 90 days of file date of the Certificate of Incorporation.)”verbatim · portal.ct.gov · retrieved 2026-09-23	Applies toA Connecticut corporation's first report is due within 90 days of the filing date of its Certificate of Incorporation. Later annual report dates are not covered here.	Due ruleNo date: see the source text	2027 dates—	Source · retrievedportal.ct.gov/-/media/SOTS/Business-Services/BSD-Forms/Corporations/Non-Stock-Corporation/Organization-and-1st-Report-Stock-or-Nonstock-r5b-FILLABLE-Corrected-042020-1.pdf (official source, opens in a new tab)retrieved 2026-09-23

Pass-through entity tax

1 date

An elective entity-level tax that partnerships and S corporations pay on their owners’ behalf. It applies only to entities that elect it.

Obligation	Applies to	Due rule	2027 dates	Source · retrieved
Form CT-PET pass-through entity tax returncalendar-year S corporation or partnership Source text “Form CT‑PET is due on or before the fifteenth day of the third month following the close of the taxable year (March 15 for calendar year filers). If the due date falls on a Saturday, Sunday, or legal holiday, the return will be considered timely if filed by the next business day.”verbatim · portal.ct.gov · retrieved 2026-09-23 “Checking off the box on a timely filed Form CT‑1065/CT‑1120SI, Connecticut Composite Income Tax Return, electing to file a Pass‑Through Entity Tax Return will constitute written notice.”verbatim · portal.ct.gov · retrieved 2026-09-23 “(a) When the final day prescribed under authority of the general statutes for performing any act which is required or permitted to be performed, by a taxpayer or by the Department of Revenue Services, in connection with any tax payable to the Commissioner of Revenue Services falls on Saturday, Sunday or a legal holiday, as defined in section 1-4, the performance of such act will be considered timely if such act is performed on the next succeeding day which is not a Saturday, Sunday or legal holiday.”verbatim · Conn. Gen. Stat. §12-39a(a) · prdext2.cga.ct.gov · retrieved 2026-09-26	Applies toA partnership or S corporation that elected the pass-through entity tax files Form CT-PET by the 15th day of the 3rd month after its taxable year closes (March 15 for calendar-year filers). A Saturday, Sunday or legal-holiday date moves to the next business day.	Due ruleCT-PET: 15th day of the 3rd month after the tax year endsIf this date falls on a Saturday, Sunday or a Connecticut legal holiday, it moves to the next business day — Conn. Gen. Stat. §12-39a(a). Not every such holiday is compiled: Days appointed or recommended by the Governor or the President as a day of thanksgiving, fasting or religious observance (§1-4) are not listed — Thanksgiving is one of them, so it is not listed.prdext2.cga.ct.gov/current/pub/chap_202.htm (official source, opens in a new tab)retrieved 2026-09-26 · Conn. Gen. Stat. §12-39a(a)	2027 dates Mar 15MonCT-PET State legal holidays are not compiled: if this date is a state holiday, the deadline moves to the next business day.	Source · retrievedportal.ct.gov/drs/taxes/pass-through-entity/tax-information (official source, opens in a new tab)retrieved 2026-09-23

Form CT-PET pass-through entity tax returncalendar-year S corporation or partnership

Source text

“Form CT‑PET is due on or before the fifteenth day of the third month following the close of the taxable year (March 15 for calendar year filers). If the due date falls on a Saturday, Sunday, or legal holiday, the return will be considered timely if filed by the next business day.”verbatim · portal.ct.gov · retrieved 2026-09-23

“Checking off the box on a timely filed Form CT‑1065/CT‑1120SI, Connecticut Composite Income Tax Return, electing to file a Pass‑Through Entity Tax Return will constitute written notice.”verbatim · portal.ct.gov · retrieved 2026-09-23

“(a) When the final day prescribed under authority of the general statutes for performing any act which is required or permitted to be performed, by a taxpayer or by the Department of Revenue Services, in connection with any tax payable to the Commissioner of Revenue Services falls on Saturday, Sunday or a legal holiday, as defined in section 1-4, the performance of such act will be considered timely if such act is performed on the next succeeding day which is not a Saturday, Sunday or legal holiday.”verbatim · Conn. Gen. Stat. §12-39a(a) · prdext2.cga.ct.gov · retrieved 2026-09-26

Applies toA partnership or S corporation that elected the pass-through entity tax files Form CT-PET by the 15th day of the 3rd month after its taxable year closes (March 15 for calendar-year filers). A Saturday, Sunday or legal-holiday date moves to the next business day.

Due ruleCT-PET: 15th day of the 3rd month after the tax year endsIf this date falls on a Saturday, Sunday or a Connecticut legal holiday, it moves to the next business day — Conn. Gen. Stat. §12-39a(a). Not every such holiday is compiled: Days appointed or recommended by the Governor or the President as a day of thanksgiving, fasting or religious observance (§1-4) are not listed — Thanksgiving is one of them, so it is not listed.prdext2.cga.ct.gov/current/pub/chap_202.htmretrieved 2026-09-26 · Conn. Gen. Stat. §12-39a(a)

2027 dates

Mar 15MonCT-PET

State legal holidays are not compiled: if this date is a state holiday, the deadline moves to the next business day.

Source · retrievedportal.ct.gov/drs/taxes/pass-through-entity/tax-informationretrieved 2026-09-23

Due-date rules

no fixed date

The conventions other lines cite: how a date on a weekend or holiday moves, and how a disaster declaration postpones deadlines.

Obligation	Applies to	Due rule	2027 dates	Source · retrieved
Weekend and holiday due dates Source text “If a due date happens to fall on a Saturday, Sunday or holiday, then the due date will be the next business day.”verbatim · portal.ct.gov · retrieved 2026-09-23	Applies toA Connecticut UI return due on a Saturday, Sunday or holiday is due the next business day.	Due ruleNo date: see the source text	2027 dates—	Source · retrievedportal.ct.gov/dol/knowledge-base/articles/unemployment-taxes/what-are-the-due-dates-of-my-quarterly-tax-returns (official source, opens in a new tab)retrieved 2026-09-23

Dates are computed from the linked pages as they read on each retrieval date. Agencies change their pages, and the IRS postpones deadlines after disasters; confirm with the source before filing.

Tracking these for a list of clients? FilingDates builds each client’s calendar from the same rules, with every date linked to its source.