S Corporation Tax Deadlines in Connecticut
Federal and state filing dates, extensions, and estimate schedules for 2026.
Connecticut filing deadline
CT S corporation returns due March 15 (next business day if weekend).
Due: Mar 16, 2026
Extension: Sep 15, 2026
Form: Form CT-1120SI
Estimated payments
No state estimated payment schedule listed.
Due: N/A
FAQ
Does Connecticut require S Corporation estimated payments?
Estimated payments are not typically required at the entity level, but confirm with Connecticut Department of Revenue Services.
Where can I file Connecticut S Corporation taxes?
Use Connecticut Department of Revenue Services resources at https://portal.ct.gov/DRS for forms and filing instructions.