Filing 2021 State Income Taxes in Connecticut

Filing 2021 State Income Taxes in Connecticut
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As you get ready to prepare your individual Connecticut income tax, you'll want to have the correct tax forms, as well as the right information for how and where to file them. You'll also want to know exactly where you fall among Connecticut's seven state income tax brackets.

Who Must File Connecticut Income Taxes?

Full-year residents of Connecticut must file a resident income tax return if they had Connecticut income tax withheld, made estimated tax payments to Connecticut, are claiming an earned income tax credit in Connecticut, had a federal alternative minimum tax liability, or pass Connecticut's Gross Income Test, which means your income exceeds certain amounts:

  • $12,000​ if married filing separately
  • $15,000​ if filing single
  • $19,000​ if filing as head of household
  • $24,000​ if filing jointly or are a qualifying widower with a dependent child

Someone who changed their legal residence to or from Connecticut during the current tax year is considered a part-year resident and must pay Connecticut taxes on all income earned in Connecticut in the tax year. Nonresidents who earn any income from a Connecticut source or for performing work in Connecticut must file a Connecticut state income tax return.

Special accrual rules apply to part-year residents and there are directions for how to account for this on the part-year resident return form.

What Are the Forms to Use?

The general Connecticut income tax form is CT-1040. Detailed instructions for this form, along with related schedules and worksheets, can be found in the 2021 Connecticut Resident Income Tax Instruction Booklet.

Nonresidents and part-year residents fill out CT-1040NR/PY as well as Schedule CT-SI and Schedule CT-1040 AW as needed. Those with a change of residency status may complete form CT-12-717A or CT-12-717B related to the special accrual rules.

Full-year residents of Connecticut filing for the 2021 Connecticut Earned Income Tax Credit (EITC) submit Schedule CT-EITC. Part-time and nonresidents do not qualify for the Connecticut EITC.

If you have already filed a return in Connecticut and would like to apply for the Connecticut EITC, submit Form CT-1040X, the Amended Connecticut Income Tax Return for Individuals.

All other individual forms and schedules related to specific tax situations can be found on CT.gov, the website of the Connecticut Department of Revenue Services (DRS).

To e-file for free through Connecticut's online service, visit the Taxpayer Service Center (TSC-IND), Connecticut's one-stop filing center for taxpayers.

What Is the Tax Rate in Connecticut?

Connecticut has a tiered tax structure with seven tax brackets, ranging from ​3 percent​ to ​6.99 percent​, depending on an individual's total taxable income:

  • 3.0 percent​ for singles in the $0 and $10,000 range or those filing joint/head of household in the $0 to $20,000 range
  • 5.0 percent​ for singles in the $10,001 to $50,000 range or those filing joint/head of household in the $20,001 to $100,000 range
  • 5.5 percent​ for singles in the $50,001 to $100,000 range or those filing joint/head of household in the $100,001 to $200,000 range
  • 6.0 percent​ for singles in the $100,001 to $200,000 range or those filing joint/head of household in the $200,001 to $400,000 range
  • 6.5 percent​ for singles in the $200,001 to $250,000 range or those filing joint/head of household in the $400,001 to $500,000 range
  • 6.9 percent​ for singles in the $250,001 to $500,000 range or those filing joint/head of household in the $500,001 to $1,000,000 range
  • 6.99 percent​ for singles over $500,000 or those filing joint/head of household over $1,000,000

If you have already filed your federal tax return, your federal Adjusted Gross Income (AGI) is the amount you will use to know your Connecticut tax bracket. You can estimate the amount of your Connecticut income tax on the State of Connecticut DRS tax calculator.

What Are the Filing Deadline and Extension Process?

Individual Connecticut state income tax returns are due by ​Monday, April 18, 2022​. The due date for filing under a valid extension is ​Monday, October 17, 2022.​ An extension allows you ​six​ more months to file taxes, but any taxes owed must still be paid by April 18, 2022.

If you are filing for an extension and you owe Connecticut tax, you must file Form CT-1040EXT and include a valid cause for your request.

If you owe Connecticut tax and have already filed a federal extension request with the Internal Revenue Service (IRS), you must file Form CT-1040EXT, but do not need to provide a cause. If you filed for a federal extension and do not owe any Connecticut tax, you do not need to file a Connecticut extension form.

You may file an extension request electronically through the Connecticut Department of Revenue Services Taxpayer Service Center (TSC).

All extension requests, along with payment of any tax due, must be submitted electronically or postmarked on or before the original due date for filing returns, ​Monday, April 18, 2022​, to avoid penalty and interest​.

What Are the Penalties for Late Filing and Underpayment of Taxes?

If your tax return is not received by ​April 18, 2022,​ any outstanding balance on taxes owed is subject to a ​10 percent penalty​. Each month or fraction of a month that a payment remains unpaid, ​1 percent​ interest will be charged.

Late filers who wish to apply for a penalty waiver may file Form DRS-PW, the Request for Waiver of Civil Penalty. To be eligible for a waiver, you must first pay all taxes and interest due. Then you may submit the form electronically or by mail to: Department of Revenue Services, Operations Bureau/Penalty Waiver, PO Box 5089, Hartford, CT 06103.

Where Do I Mail/E-file My Connecticut Return?

E-filing can be done at no cost through TSC-IND, the Connecticut DRS portal for electronically filing, making payments and viewing your account. You may also file with commercial tax assistance software.

If you are filing a paper income tax return with a payment, mail it to: Department of Revenue Services, PO Box 2977, Hartford CT 06104-2977. To file a paper income tax return without a payment, mail it to: Department of Revenue Services, PO Box 2976, Hartford CT 06104-2976.

Checks should be made payable to: "Commissioner of Revenue Services" and include the tax year and form number in the memo.

How Do I Pay Taxes Due?

For e-filers, the most convenient way to pay taxes due is to set up an electronic funds transfer or credit or debit card payment at the time of filing. You may also send a check by mail. To file a paper return with a payment, you may also mail a check or make your tax payment online.

Before mailing a payment, check your tax booklet or the Mailing Addresses page of the CT.gov website to ensure you are sending your form to the correct PO Box.

If you have difficulty paying your Connecticut tax bill, the DRS offers installment agreements and payment assistance for qualifying taxpayers.

Where Can I Check My Connecticut Refund Status?

To check the status of your Connecticut tax refund, visit the online portal. You may also call the automated refund system, which is available ​24 hours​, at ​800-382-9463​ (or ​860-297-5962​ in the Greater Hartford calling area). Either way, you will need your Social Security number and the exact amount of your refund on your income tax return.

Paper returns will take ​10 to 12 weeks​ for processing before being available for a status check.

What About Connecticut State Taxes if You’re Self-employed?

Self-employed taxpayers in Connecticut should be making quarterly estimated Connecticut Income Taxes with Form CT-1040ES, with the first payment for 2022 due on ​April 18, 2022​. You can use IP-93(6.3) to help calculate your estimated tax installments.

What About Connecticut State Taxes if You’re a Business?

If your business is not exempt, the Connecticut corporate tax rate is ​7.5 percent.​ Business tax returns in Connecticut are due on the fifteenth day of the month following the due date of the federal income tax return. Check the CT.gov portal for specifics about business taxes in Connecticut.

The rates and dates in the article are correct as of publication, but check for any changes at the Connecticut State Department of Revenue website when you are ready to file.