Connecticut has a state income tax, and it applies to most residents and workers

Yes, Connecticut charges state income tax on wages, investment income, and other earnings. The tax rate varies based on your income level — Connecticut uses a progressive tax system with rates ranging from 3% to 6.99% depending on your tax bracket. If you live in Connecticut, work there, or earn income from Connecticut sources, you will owe state income tax unless you fall into a specific exemption category.

The Connecticut Department of Revenue Services administers the tax. You file your state return using Form CT-1040 (the main individual income tax form) or Form CT-1040NR if you are a nonresident. Most people file their state return at the same time as their federal return, using the same income figures as their starting point.

Key Takeaways

  • Connecticut income tax rates range from 3% to 6.99% depending on your income bracket, with higher earners paying the top rate.
  • You must file a Connecticut return if you lived in the state for any part of the tax year and had income above the filing threshold, which varies by filing status.
  • Certain types of income — including Social Security benefits, military pensions, and some retirement distributions — are partially or fully exempt from Connecticut tax.
  • If you moved to or from Connecticut during the year, you may file as a part-year resident and owe tax only on income earned while you lived there.
  • Connecticut allows credits for taxes paid to other states, so you typically do not pay tax twice on the same income.

Connecticut income tax brackets and rates for the current year

Connecticut's tax brackets change each year because they are adjusted for inflation. The state publishes updated brackets in the spring for the tax year you are filing. For the 2024 tax year (filed in 2025), the rates and brackets depend on your filing status — single, married filing jointly, married filing separately, or head of household.

The lowest bracket starts at 3% and the highest reaches 6.99%. Your actual tax bill depends on which bracket your income falls into. For example, if you are single and earn $50,000, only the portion of your income that falls into each bracket is taxed at that bracket's rate — you do not pay 6.99% on all $50,000. The Connecticut Department of Revenue Services publishes a tax table each year showing the exact tax owed at different income levels, which is simpler than calculating brackets yourself.

You can find the current year's brackets and tax tables on the Connecticut Department of Revenue Services website. The site also has a tax calculator tool where you can enter your income and filing status to see an estimate of what you owe.

Who must file a Connecticut income tax return

You must file a Connecticut return if you lived in Connecticut for any part of the tax year and your income exceeded the filing threshold for your situation. The threshold varies by age and filing status. Generally, if you are under 65 and single, you must file if your income is above a certain amount (this amount changes yearly). If you are 65 or older, the threshold is higher. If you are married filing jointly, the threshold is higher still.

Even if your income is below the threshold, you should file if you had Connecticut income tax withheld from your paychecks or made estimated tax payments. Filing allows you to claim a refund of any overpayment. You should also file if you are claiming the Earned Income Tax Credit or other refundable credits, since these can result in a refund even if you owe no tax.

If you moved to Connecticut during the year, you file as a part-year resident. If you moved out of Connecticut during the year, you also file as a part-year resident. In both cases, you owe Connecticut tax only on income you earned while you were a Connecticut resident.

Types of income that are exempt or partially exempt from Connecticut tax

Connecticut exempts certain types of income entirely or allows you to exclude part of it. Social Security benefits are not taxed by Connecticut, even though they may be taxable at the federal level. Military pensions and some other government pensions receive preferential treatment — you may be able to exclude part or all of them depending on your age and when you earned the pension.

Retirement distributions also receive special treatment. If you are 60 or older, you can exclude up to $6,000 per year of retirement income from pensions, annuities, and distributions from retirement accounts like IRAs and 401(k)s. This exclusion applies to distributions from any source, not just government pensions. If you are younger than 60, you cannot use this exclusion unless the distribution is from a government pension.

Interest and dividends from certain investments may also receive preferential treatment under Connecticut law, though the rules are complex and depend on the type of investment and when you earned the income. The Connecticut Department of Revenue Services publishes detailed guidance on which types of income may have access to for each exemption.

How to file your Connecticut income tax return

You file your Connecticut return using Form CT-1040 if you are a resident, or Form CT-1040NR if you are a nonresident. You can file by mail or electronically. Most tax software that handles federal returns also handles Connecticut returns — you straightforward select Connecticut as your state when you set up your return. If you use a tax preparer, they will file your state return along with your federal return.

Your Connecticut return uses the same income figures as your federal return as a starting point. You then make adjustments for items that are treated differently under Connecticut law — for example, adding back any Social Security benefits you excluded from federal tax, or subtracting retirement income that Connecticut exempts. The form walks you through these adjustments step by step.

The important date to file your Connecticut return is the same as the federal important date — normally April 15. If you file for a federal extension, your Connecticut return is also extended to the same date. You can request an extension online through the Connecticut Department of Revenue Services website or by filing Form CT-1040-EXT.

Credits and deductions available to Connecticut taxpayers

Connecticut offers several credits that reduce your tax bill dollar-for-dollar. The Earned Income Tax Credit is available to lower-income workers and is often larger than the federal credit. The Child and Dependent Care Credit helps pay for childcare expenses. The Education Credit covers tuition and fees at colleges and universities. These credits are in addition to any federal credits you claim.

Connecticut also allows a credit for taxes paid to other states. If you earned income in another state and paid tax there, you can claim a credit on your Connecticut return to avoid paying tax twice on the same income. This credit is particularly important for people who work in one state and live in another. You calculate the credit using Form CT-1040-CR.

Standard deductions and itemized deductions work similarly to the federal system. Connecticut allows you to take either the standard deduction (which varies by filing status and age) or to itemize your deductions. Most people take the standard deduction because it is simpler and results in a lower tax bill.

What happens if you do not file or pay Connecticut income tax

If you owe Connecticut income tax and do not file or pay, the state can assess penalties and interest. The penalty for failing to file is normally 5% of the unpaid tax per month, up to a maximum of 25%. The penalty for failing to pay is normally 0.5% of the unpaid tax per month, up to a maximum of 25%. Interest accrues daily on any unpaid balance at a rate set by the state each quarter.

The Connecticut Department of Revenue Services can also place a lien on your property, garnish your wages, or offset your state refunds to collect unpaid tax. If you owe a large amount, the state may refer your case to a collection agency. If you cannot pay in full, you can request a payment plan or an offer in compromise (settling for less than you owe) by contacting the department directly.

If you realize you did not file in a previous year, you can still file that return. Filing late is better than not filing at all, because it stops the failure-to-file penalty from accruing further. If you are owed a refund, you have three years from the original due date to claim it.

Frequently Asked Questions

Do I have to pay Connecticut income tax if I work in Connecticut but live in another state?

Yes, you owe Connecticut income tax on wages you earned while working in Connecticut, even if you live elsewhere. You file as a nonresident using Form CT-1040NR and report only your Connecticut-source income. You can claim a credit on your home state's return for taxes paid to Connecticut to avoid double taxation.

What if I moved to Connecticut partway through the year?

You file as a part-year resident and owe Connecticut tax only on income earned after you moved to the state. You report your pre-move income on your previous state's return (or federal return only if you had no state of residence). The Connecticut return asks for the date you became a resident, and you report income starting from that date.

Are retirement distributions taxed differently in Connecticut than at the federal level?

Yes. Connecticut allows you to exclude up to $6,000 per year of retirement income if you are 60 or older, regardless of the source. This is more generous than the federal treatment, which taxes most retirement distributions as ordinary income. If you are younger than 60, the exclusion applies only to government pensions.

Can I file my Connecticut return without filing a federal return?

You can file a Connecticut return even if you have no federal filing requirement, but most people file both at the same time because Connecticut uses federal income as the starting point. If you have no federal income but earned Connecticut-source income, you should file a Connecticut return to report that income and pay any tax owed.

What if I disagree with my Connecticut tax bill?

You can file a protest with the Connecticut Department of Revenue Services within 30 days of receiving a notice of assessment. The protest must explain why you believe the assessment is wrong and include supporting documents. The department will review your protest and either adjust the assessment or uphold it. If you disagree with the result, you can appeal to the Connecticut Tax Tribunal.