Sole Proprietorship Tax Deadlines in Connecticut
Federal and state filing dates, extensions, and estimate schedules for 2026.
Connecticut filing deadline
Business income reported on CT personal return.
Due: Apr 15, 2026
Extension: Oct 15, 2026
Form: Form CT-1040
Estimated payments
Estimated payment dates: Apr 15, 2026, Jun 15, 2026, Sep 15, 2026, Jan 15, 2027.
Due: Apr 15, 2026
FAQ
Does Connecticut require Sole Proprietorship estimated payments?
Estimated payments are scheduled for Apr 15, 2026, Jun 15, 2026, Sep 15, 2026, Jan 15, 2027.
Where can I file Connecticut Sole Proprietorship taxes?
Use Connecticut Department of Revenue Services resources at https://portal.ct.gov/DRS for forms and filing instructions.