Connecticut

Corporate income tax

Corporation Business Tax return (Form CT-1120) is due on or before the 15th day of the month following the due date of the corporation's federal return (June 30 year ends: October 15).

Extension. Six-month extension via Form CT-1120 EXT (seven months for June 30 year ends), i.e., to the 15th day of the 11th month (November 15 for calendar year)

Partnerships and S corporations

The Connecticut Pass-Through Entity (PE) Tax, mandatory for 2018-2023, is optional for taxable years beginning on/after 1/1/2024 (PA 23-204): the annual, irrevocable election is made by checking the box on a timely filed CT-1065/CT-1120SI. S corporations are not subject to the Corporation Business Tax.

Sales and use tax

Due date. Form OS-114 and payment due on or before the last day of the month following the end of the filing period; annual filers file by January 31.

Filing frequency. Assigned by DRS (monthly, quarterly or annual) based on total tax liability for the 12-month period ending the preceding June 30 (Conn. Gen. Stat. 12-414(a)).

Thresholds. Annual: prior 12-month (ending June 30) liability less than $1,000; quarterly: $1,000 or more but less than $4,000; monthly: $4,000 or more.

Prepayments. No general prepayment; 12-414(e)(2) lets the Commissioner require weekly remittance from certain sellers (not detailed here). Returns must be filed and paid electronically via myconneCT.

Notes

The PE tax became elective for 2024 and later years. Annual reports are filed with the Secretary of the State (fee raised to $80 for LLCs/LPs/LLPs when the BET was repealed) and were not chased.