Connecticut continues to rank among the most challenging states for taxpayers. According to the Tax Foundation’s 2023 State Tax Competitiveness Index, the state landed 47th overall for tax burden, with only New York, New Jersey, California, and the District of Columbia ranking lower. The report points to Connecticut’s use of every primary tax type and one of the country's most complicated individual income tax systems.
The state’s tax structure includes a graduated income tax ranging from 2.00 to 6.99 percent, a 7.5 percent corporate income tax, and a 6.35 percent statewide sales tax, with no local sales taxes. Homeowners also face a property tax rate of roughly 1.78 percent. For many residents and small business owners, navigating these layers of taxation can be confusing—especially when preparing a Connecticut income tax return.
This guide explains how to file your Connecticut tax return for 2023, including who must file, how to calculate your federal adjusted gross income, which forms to use, and what deadlines to meet. Whether you’re a full-time resident, a part-year resident, or someone with Connecticut sources of income, knowing what to do now can help you avoid errors and stay compliant.
Filing a Connecticut income tax return is not just for full-time residents. Whether you lived in the state for the entire year, moved partway through 2023, or earned income from Connecticut sources, your filing obligation depends on your residency status, income level, and other factors outlined by the Department of Revenue Services.
You’re considered a resident if Connecticut was your permanent legal residence during 2023 or if you maintained a permanent place of abode in the state and spent more than 183 days here. Residents must file a resident income tax return if any of the following apply:
If you were a part-year resident—meaning you moved into or out of Connecticut during 2023—you may still be required to file. Use Form CT-1040NR/PY and report income earned while you were a resident and any income from Connecticut sources while living elsewhere.
You are a Connecticut non-resident if you lived outside the state for all of 2023 but earned income from Connecticut. Filing is required if:
You must file if your gross income exceeds the following limits for your filing status:
Gross income includes all income from all sources—earned income, interest, dividends, capital gains, unemployment, business income, and even treaty income—regardless of whether it's taxed federally. If you're unsure about your filing status or whether your income requires a return, consider speaking with a tax professional or using Connecticut’s online filing tools to determine your obligation.
Knowing which forms apply to your situation before you start preparing your Connecticut income tax return is essential. Most filers will use the state’s standard forms, but others may need to attach schedules for credits or special types of income. The Department of Revenue Services (DRS) website provides all official forms and instructions.
Depending on your situation, you may need to include additional forms to claim certain deductions or tax credits:
Before completing your state forms, you’ll need a copy of your federal income tax return, as Connecticut begins with your federal adjusted gross income to calculate your state tax. Be sure to have your federal Form 1040 completed first. Most state forms will require numbers pulled directly from that return.
All 2023 tax forms and their instructions can be downloaded or filled out electronically via the official CT DRS site at portal.ct.gov/DRS. You’ll also find guides and bulletins from the revenue services office to help clarify any uncertainties about which forms to use.
Filing your Connecticut income tax return involves more than just entering a few numbers. To avoid errors and delays, it helps to follow a structured approach. Below is a breakdown of each step, from gathering documents to claiming credits and verifying final figures.
Before you begin, make sure you have:
Having this information ready will help you complete your return more efficiently.
Connecticut calculates taxable income beginning with your federal adjusted gross income (AGI) from federal form 1040, Line 11. This figure reflects your total income minus specific federal deductions and adjustments. You must complete your federal return for federal income tax purposes first, since Connecticut builds off that base amount.
Connecticut may require you to adjust your federal AGI by:
These changes are calculated on Schedule 1, and the resulting number gives you your Connecticut adjusted gross income.
Next, use Connecticut’s income tax tables or the myconneCT online calculator to determine the amount of state tax you owe based on your filing status and income level.
No tax is due if your Connecticut adjusted gross income is below the thresholds for your filing status:
Connecticut offers several tax credits that can lower your final tax liability. Some of the most common include:
Ensure you’re claiming only those you’re eligible for and include any required documentation.
If you’ve already paid a portion of your tax liability during the year, this is the time to report it:
These prepayments will be subtracted from your total tax to determine your payment due or refund.
Before you submit:
If you plan to file tax returns electronically, you’ll receive confirmation once submitted. If mailing, use the correct address and include your payment if required.
While rare, some individuals may be exempt from filing due to income thresholds, age, or specific treaty conditions. For instance, students or retirees with limited earned income may not be required to file. Use the gross income test and residency definitions to confirm.
Filing your Connecticut state return can be done in two primary ways: electronically or on paper. While both options are available, Connecticut’s Department of Revenue Services (DRS) strongly encourages taxpayers to e-file whenever possible.
The e-file method is the fastest, most accurate, and most secure way to file taxes. Here’s why it works best for most filers:
You can e-file for free using the myconneCT portal at portal.ct.gov/DRS-myconneCT, or use approved third-party tax preparation software. If you’re filing federal and state returns, e-filing can streamline the process by pulling relevant numbers directly from your federal forms.
Paper filing is still an option, though it takes longer to process—typically 10 to 12 weeks. If you choose to file by mail:
If you aim for a faster refund or have a more straightforward tax situation, e-filing is almost always the better choice. However, individuals who don’t have online access or prefer paper can still file by mail. Just be sure to file early and double-check all documentation.
Whether you owe taxes or are expecting a refund, understanding the payment and refund process is key to correctly completing your Connecticut income tax return. The Department of Revenue Services (DRS) offers several options for securely submitting payments or receiving your refund.
The easiest way to pay what you owe is through the myconneCT portal at portal.ct.gov/DRS-myconneCT. You can pay using:
This method is secure, accessible 24/7, and gives immediate payment confirmation. It’s also processed faster than mailed checks.
By Check
If you prefer to pay by check:
Mail your check to the appropriate address listed on the filing instructions.
If your payment is late, Connecticut applies:
To avoid these IRS-style penalties, submit your return and payment by April 15, 2024. Extensions to the file don’t extend the time to pay.
If you’re expecting a refund, you can check its status online through myconneCT by selecting “Where’s My Refund?” You'll need:
You can also check by phone at 800-382-9463 (outside Hartford) or 860-297-5962.
Direct deposit is the fastest refund option, but it is not available for first-time Connecticut filers. Make sure your financial institution and routing numbers are correct. Whether sending money to the state or waiting for a refund, filing accurately and on time helps avoid delays and unwanted notices from revenue services.
Even a small error on your Connecticut income tax return can lead to delays in processing, missing out on credits, or receiving a reduced refund. Before you file, make sure to double-check everything. Here are some of the most common mistakes that cause problems for filers each year.
This is one of the most frequent oversights. Both spouses must sign a joint return. Unsigned forms are considered incomplete and won’t be processed until corrected.
Connecticut has different addresses depending on whether you’re submitting a payment, requesting a refund, or sending only documentation. Sending your taxes to the wrong place can delay the entire filing process.
Make sure all Connecticut income tax withheld amounts match your W-2s and 1099s and that you’ve entered figures into the correct columns on the return.
All figures on the return must be rounded to the nearest whole dollar. Using cents or estimating loosely can trigger errors and delays.
Attach the correct forms or schedules to claim credit or adjustment. Missing documentation could cause your return to be flagged or adjusted.
You may face penalties and interest if you miss the April 15 filing date and owe taxes. Filing a late return without paying on time can add to your bill.
Always save a complete return copy, including proof of schedules and payment. This is helpful if you need to amend your return later or verify income for future applications. Taking time to avoid these errors can help ensure that your return is processed smoothly and without delays by Connecticut revenue services.
Missing the deadline to file your state income tax return doesn’t necessarily mean you’re in trouble, but you’ll need to act quickly to limit penalties or interest. In Connecticut, the deadline for tax filing is April 15, 2024. If you need more time, you can request an extension by submitting Form CT-1040 EXT, but you must pay any estimated income tax owed by the original deadline.
Filing an extension gives you until October 15, 2024, to submit your completed Connecticut income tax return, but it does not extend the time to make a payment. If you expect to owe, you must prepare an estimate and submit a payment with your extension to avoid late fees. You can access this form and make payments through the myconneCT portal.
If you are a resident or nonresident with Connecticut income and missed the deadline, file your return as soon as possible. Penalties apply if you owe and have not filed or paid on time, but there's no penalty if no tax is due.
If you discover an error after filing—such as missing deductions, property tax credits, or corrected W-2s—you can submit an amended return using Form CT-1040X. The state recommends you wait until your original return has been processed before sending an amendment. For tricky situations or multi-state filings, it may be wise to consult tax experts who are familiar with Connecticut’s income tax system and rules for adjustments.
Before you submit your Connecticut income tax return, take a few minutes to double-check everything. A simple mistake or missing document can delay your refund or result in unnecessary follow-up from the Department of Revenue Services.
Use this checklist to ensure your return is complete and ready to go:
Filing early also gives you more time to catch mistakes, respond to missing documents, and ensure the maximum refund possible. If your return is straightforward, you may qualify to file for free using myconneCT or other approved tax software providers. Don’t forget to account for how much time you’ve spent preparing—double-checking now can help you avoid paying more later.
If you’ve already submitted your CT state return and haven’t received a refund or notice, check your status using the myconneCT portal or call DRS directly. Processing times vary, especially for paper returns, but most e-filed returns are handled faster. Ensure your information is accurate and your banking details were submitted correctly.
The tax filing deadline for Connecticut is April 15, 2024. Missing this date can lead to penalties and interest if taxes are owed. However, filing late with no balance due may result in only a flat $50 penalty. To stay in good standing, submit your CT state return and any payment promptly, even after the due date.
Anyone who was a resident for the whole year and meets income thresholds, had Connecticut tax withheld, or is claiming credits like the CT EITC must file a Connecticut resident income tax return. Use Form CT-1040 and ensure your CT state return includes accurate reporting of all sources of income and payments made during the year.
You can file your taxes using the myconneCT portal or approved e-file providers, especially if your situation is simple. Most taxpayers can complete their CT state return without professional help, but those with complex income sources or multi-state issues may benefit from guidance. Always review your return carefully before submitting it.
Review all applicable credits and deductions, including property tax relief and the CT EITC, to maximize your refunds. Using myconneCT or tax software helps ensure accurate state return calculations. Double-check that all supporting schedules are included and that you’ve entered exact figures from your W-2s and 1099s.
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