2018 State of CT Income Tax Filing Requirements

CT Resident Income Tax Return

You must file a Connecticut resident income tax return if you were a resident of CT for the entire year and any of the following applies to you for the 2018 calendar year:

  • You had CT income tax withheld;
  • You made estimated tax payments to CT;
  • You made an extension payment to CT;
  • You meet the gross income test (see below);
  • You had a federal alternative minimum tax liability;
  • You are claiming the Connecticut earned income tax credit (CT EITC); or
  • You had a Pass-Through Entity Tax Credit (PE Tax Credit) amount which does not fully offset your CT tax liability.

If none of the above apply, do not file a CT resident income tax return.

CT Gross Income Test

Filing Status Gross Income1 is at least
Single $15,000
Married Filing Jointly $24,000
Married Filing Separately $12,000
Head of Household $19,000
Qualifying Widow(er) with dependent child $24,000

1 Gross income generally means all income you received from all sources in the form of money, goods, property, services, not exempt from federal income tax, and any additions to income required to be reported on Form CT-1040, Schedule 1.

For items of gross income generally pertaining to students, please refer to IRS Publication 970, Tax Benefits for Education, Chapter 1, Scholarships, Fellowships, Grants and Tuition Reductions and the IRS web page for students, Student’s Page - Higher Education.

CT Non-resident and Part-year Resident Income Tax Return

You must file a Connecticut Non-resident or Part-Year resident income tax return if you were a nonresident or part-year resident of CT for the year and any of the following applies to you for the 2018 calendar year:

  • You had CT income tax withheld;
  • You made estimated tax payments to CT;
  • You made a CT extension payment;
  • You were a part-year resident who meets the gross income test (see above) or who had a federal alternative minimum tax liability;
  • You were a non-resident with any CT source income who meets the gross income test (see above) or had a federal alternative minimum tax liability; or
  • You had a Pass-Through Entity Tax Credit (PE Tax Credit) amount which does not fully offset your CT tax liability.

If none of the above apply, you are not required to file a CT Nonresident or Part-Year resident income tax return.

For information on residency, please refer to the Form CT-1040 Instructions (page 10) and the CT DRS Filing Requirements for Students.

Note: This guide does not address tax filing obligations for states other than Connecticut. If you were a resident of another state for all or part of the calendar year 2018 and/or you earned income in another state in 2018, you may be required to file tax returns in additional states.