State Income Tax Filing

Connecticut state capitol building

Who Needs to File a Connecticut State Return?

You must file a Connecticut (CT) state income tax return if any of the following is true for the 2020 tax year. The filing deadline for your 2020 CT tax return has been extended to May 17, 2021.  If none apply, you do not need to file a 2020 CT return. For more information about filing your CT state return, visit the Yale Tax Office website.

  • you had CT income tax withheld, or
  • you had made estimated tax payments to CT, or
  • you had a federal alternative minimum tax liability, or
  • you meet the Gross Income Test – for 2020, if your gross income exceeds:
    • $15,050 and you will file as Single, or
    • $12,050 and you will file as Married Filing Separately, or
    • $19,050 and you will file as Head of Household, or
    • $24,050 and you will file as Married Filing Jointly (each spouse/child must have a SSN or ITIN to file under this category).

Do I Need to Report Treaty Income for CT Income Tax Filing?

Federal income tax treaty provisions are not recognized for CT state income tax purposes. Any treaty income reported on your federal 1040NR or 1040NR-EZ must be added to your federal Adjusted Gross Income (AGI) on your CT-1040 (calculations are done on CT Schedule 1, line 38, write in tax treaty wages, then go to line 2 of CT-1040). For complete information, refer to Special Instructions for Nonresident Aliens of the CT Income Tax Instructions.

Sprintax Tax Preparation Software for State Returns

Sprintax offers an online solution for the preparation of state tax returns from $29.95 per return.

Access to Sprintax

Determining Your CT Tax Residency Status and Completing the Forms

In any calendar year, you could have a different status for (1) immigration, (2) federal income tax purposes, and (3) state income tax purposes. For information about “nonresident” vs. “resident” for CT income tax purposes, refer to the CT Income Tax Instructions.

  • If you a CT Resident for tax purposes, complete Form CT-1040 if you lived in CT for more than 183 days during 2019. If you have filed in CT the previous tax year, you will be eligible to use the Taxpayer Service Center (TSC-IND).
  • If you are a CT Nonresident or Part-Year Resident for tax purposes, complete CT-1040NR/PY; this form is most often used by individuals who have lived and/or worked in multiple states or resided in CT for less than 183 days in that calendar year.

Can I File Without a SSN/ITIN?

If you do not have a social security and have not received your ITIN by April 15, you can file your return without the ITIN by attaching a copy of the federal Form W-7. The CT Department of Revenue Services (DRS) will contact you upon receipt of your return. DRS will hold your return until you receive your ITIN and forward the information to them. If you fail to submit the information requested, the processing of your return will be delayed. Please refer to the CT Department of Revenue Services for more information on this topic.

Print, Sign, and Mail

If you are filing as resident, you can file online with Webfile. If not, remember to sign and date your forms. CT does not require copies of your income statements for your state income tax return. If you owe money, make your check payable to: Commissioner of Revenue Services.

Keep Copies!

Remember to keep copies of what you file each year (in case your return gets reviewed and there is a problem or if the CT Department of Revenue audits you in the future).

Income Tax Filing With Other States

If you earned income in another state (for example, if you (as a student) had a paid summer internship in NY in 2019 or if you (as a student or scholar) transferred from another U.S. institution in another state to Yale in 2019), you may need to file an income tax return for the state in which you earned income. You will need to refer to the information from that particular state's Department of Revenue.

Where's My Refund?

If you have determined that you are due a refund for state income tax purposes, it will take the CT Department of Revenue Services some time to process your refund. If you submit your return(s) on or close to the filing deadline, it is not uncommon to have to wait several weeks (sometimes 10 to 12 weeks) before receiving your refund or a notice. You can check the status of your return with the CT Department of Revenue Services for your state refund.


This information is intended only for international students and scholars who are nonresident tax filers with income sources and level typical of students and scholars at Yale University. Although the information contained in this site has been reviewed carefully and should be adequate to assist most international students and scholars, it is not a substitute for advice obtained from the Connecticut Department of Revenue Services (DRS) or a qualified tax accountant. If your visa status has changed in the past year, or you believe you have a complicated tax issue, please consult the DRS or a qualified tax accountant.