Connecticut does have a state income tax

Yes, Connecticut has a state income tax. The state taxes wages, investment income, and other earnings. The tax rate varies depending on your income level — Connecticut uses a progressive tax system, meaning higher earners pay a higher percentage. If you work in Connecticut or live there, you will owe state income tax on most types of income.

Connecticut's Department of Revenue Services administers the income tax. You file a state return separate from your federal return, usually at the same time. The state tax year runs January 1 through December 31, the same as federal tax.

Key Takeaways

  • Connecticut taxes income at rates ranging from 3% to 6.99%, depending on your total income for the year.
  • You must file a Connecticut state return if you earned income in the state or lived there for the full tax year, even if you owe no tax.
  • Certain types of income, such as Social Security benefits and some retirement distributions, are not taxed by Connecticut.
  • If you moved to or from Connecticut during the year, you may file a part-year resident return instead of a full-year return.
  • Connecticut offers a property tax credit and a dependent exemption that can lower the amount of tax you owe.

Connecticut's income tax rates and brackets

Connecticut's income tax brackets change each year. The state adjusts them for inflation. For the 2024 tax year, the rates start at 3% on the lowest bracket and go up to 6.99% on the highest. The exact income thresholds that trigger each rate are published by the Department of Revenue Services each January.

The brackets explore to your federal taxable income, not your gross income. This means you calculate your federal return first, then use that number to determine your Connecticut tax. If you are married filing jointly, your brackets are wider than if you file as single.

Who must file a Connecticut state return

You must file a Connecticut return if you lived in the state for the full tax year and your income exceeds the filing threshold. The threshold depends on your filing status and age. A single person under 65 with income over a certain amount must file; the threshold is higher for people 65 and older. Married couples filing jointly have a higher threshold than single filers.

If you lived in Connecticut for only part of the year, you may file as a part-year resident. This applies if you moved into the state or moved out during the tax year. Part-year residents only pay Connecticut tax on income earned while they lived in the state. You will need to report the date you moved and provide documentation of your residency change.

Income that Connecticut does not tax

Connecticut does not tax Social Security benefits, regardless of your income level. This is one of the few states with this rule. You also do not pay Connecticut tax on certain retirement income, including distributions from a traditional or Roth IRA up to a certain amount, and military pensions.

Long-term capital gains — profits from selling stocks or property you held for more than one year — are taxed at a lower rate than ordinary income in Connecticut. may have access to dividends also receive preferential treatment. Interest income from U.S. Treasury bonds is not taxed by Connecticut, though it is taxed by the federal government.

Deductions and credits that lower your Connecticut tax

Connecticut allows you to deduct the same federal deductions you claim on your federal return. If you itemize deductions on your federal return, you itemize on your Connecticut return. If you take the standard deduction federally, you take it in Connecticut as well.

Connecticut also offers a property tax credit if you own a home and your income is below a certain threshold. The credit is based on your property tax bill and your income. You must file a separate form to claim it. The state also allows a dependent exemption — a flat dollar amount you can deduct for each dependent — which reduces your taxable income.

How to file your Connecticut state return

You file your Connecticut return using Form CT-1040 or Form CT-1040NR, depending on whether you are a resident or nonresident. The form is available on the Department of Revenue Services website. You can file by mail or electronically through the state's e-file system.

Many tax software programs include Connecticut forms and will calculate your state tax automatically if you enter your federal information. If you use a tax preparer, they will file the state return along with your federal return. The important date to file is the same as the federal important date — usually April 15, though it may be extended if that date falls on a weekend or holiday.

What happens if you do not file or pay on time

If you owe Connecticut income tax and do not pay by the important date, the state charges interest on the unpaid amount. The interest rate is set quarterly and changes based on the federal rate. You may also face a penalty if you file late or underpay your tax.

If you cannot pay the full amount by April 15, you can request a payment plan from the Department of Revenue Services. The state will work with you to set up monthly payments. Filing your return on time, even if you cannot pay the full amount, reduces the penalties you may owe.

Frequently Asked Questions

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

Yes. Connecticut taxes income earned within the state, regardless of where you live. You file as a nonresident and pay tax only on income from Connecticut sources. You may also owe tax to your home state, but most states allow a credit for taxes paid to another state to avoid double taxation.

Is Social Security really not taxed in Connecticut?

Correct. Connecticut does not tax Social Security benefits at any income level. This applies to retirement benefits, survivor benefits, and disability benefits. You still report the income on your federal return, where it may be taxable depending on your total income.

What is a part-year resident return, and when do I file one?

A part-year resident return is filed when you moved into Connecticut or out of Connecticut during the tax year. You report only the income earned while you lived in the state. You must provide the date you moved and documentation such as a lease, utility bill, or driver's license showing your residency change.

Can I claim the Connecticut property tax credit if I rent instead of own?

No. The property tax credit is only for homeowners who pay property tax on their primary residence. Renters do not pay property tax directly, so they cannot claim this credit. However, renters may be able to claim other credits or deductions depending on their situation.

What if I moved out of Connecticut during the year — do I still file a full return?

No. If you moved out of Connecticut, you file as a part-year resident and pay tax only on income earned while you lived there. You will need to report your move-out date and provide proof such as a lease end date, utility bill, or new state driver's license showing when you left.