CT Tax Filing Information

Residents and part-year residents must file if they:

• Have Connecticut income tax withheld,
• Made estimated tax payment to Connecticut,
• Meet the gross income test, below, or
• Have a federal alternative minimum tax liability, or
• Claim the Connecticut Earned Income Tax Credit.

Gross income test (must file if it exceeds):

• Married Filing Separate: $12,000
• Single: $15,000
• Married Filing Jointly: $24,000

Gross income includes all income not exempt from federal tax and any Connecticut additions to income.

Generally, nonresidents must file if they meet the filing requirements, above, and have any Connecticut-source income.

• Individual Return Due Date: April 15th
• C-Corporation Return Due Date: May 15th
• S-Corporation/Partnership/LLC: April 15th
• Business Entity Tax: April 15th (only once every two years… click here for more information).

Connecticut allows an automatic extension to October 15 if no additional tax is due and if a federal extension request is filed. If additional tax is due, file Form CT1040 EXT, Application for Extension of Time to File Connecticut Income Tax Return for Individuals, to request an extension to October 15. If federal Form 4868 has been filed with the IRS, no reason for the request is required. An extension of time to file does not extend the time to pay tax due.

Connecticut has both a corporate income tax (which Connecticut calls its corporation business tax) and a business entity tax. The business entity tax applies to all common limited liability entities other than C corporations: S corporations, LLCs, limited liability partnerships, and limited partnerships. The tax is assessed and due once every two years and the minimum tax is $250.

S-Corporations. Connecticut recognizes the federal S election, and Connecticut S corporations are not required to pay corporation business tax to the state (however they do have to pay the business entity tax).