If you are not a resident of Connecticut, but you have income derived from sources in Connecticut, you may be required to file and pay Connecticut state income tax. If you were a part-year resident of Connecticut, you are subject to Connecticut state tax on all your income from all sources during the part of the year you are a Connecticut resident, and on income from Connecticut sources during the part of the year you are a nonresident.
According to the Connecticut Department of Revenue Services, you are considered a resident of Connecticut if that is where you have your permanent legal residence or domicile. This is the place you intend to have as your permanent home and where you intend to return whenever you are away. You would also be considered a Connecticut resident if you maintained a permanent place of abode in Connecticut and spent more than 183 days in the state during the tax year.
But there are cases in which you could be considered a nonresident even if your domicile was Connecticut. One case would be if you did not maintain a permanent place of abode in Connecticut for the entire year, you did maintain a permanent place of abode outside Connecticut for the entire year, and you did not spend more than 30 days in Connecticut during the year.
The other case would be if you were in a foreign country for at least 450 days during a period of 548 consecutive days, and during that period you did not spend more than 90 days in Connecticut and did not maintain a permanent place of abode in Connecticut where your spouse or children spent more than 90 days. The 90 day limit would be determined proportionally for the years the 548-day period begins and ends.
If you are a nonresident, you would have to file a Connecticut state income tax return if you have income from Connecticut sources and your gross income from all sources is over a certain amount based on your filing status, or you have a federal alternative minimum tax liability. You can find the Filing Requirements on the Connecticut Department of Revenue Services website. You should also file a Connecticut tax return if you had Connecticut tax withheld from your pay or other sources of income, or if you made estimated tax payments to Connecticut.
Connecticut source income includes salaries or wages for services performed in Connecticut, accrued sick pay and vacation pay earned while working in Connecticut, and severance pay and unemployment benefits related to work performed in Connecticut. Connecticut source income also includes income from the rental or sale of real or tangible personal property located in Connecticut. Interest, dividends, or gains from the sale or exchange of intangible personal property is not considered Connecticut source income unless the property is employed in a business, trade, profession, or occupation carried on in Connecticut.
Connecticut source income also includes income from a partnership or S corporation doing business in Connecticut; income from a trust or estate derived or connected with sources in Connecticut; and income from a trade, profession, occupation or business carried on in Connecticut.
Winnings from the Connecticut Lottery would generally be subject to Connecticut state tax if you are issued a federal Form W-2G. This form would be issued if your winnings were $600 or more, or at least 300 times the amount of the wager.
As indicated by the Connecticut Department of Revenue Services, certain income is not included in Connecticut source income for nonresidents. This includes distributions from qualified pension or retirement plans, dividends from a corporation doing business in Connecticut, interest earned from a Connecticut bank, and compensation from an interstate rail, motor, or motor private carrier.
Income you received from activities in Connecticut that are considered casual, isolated, or inconsequential are not subject to Connecticut state tax. This would be the case if a nonresident’s presence in Connecticut does not generate more than $6,000 in gross income. But this would not apply to income from a pass-through entity such as a partnership or S corporation. In that case, gross income would have to be less than $1,000 to meet this test.
An employee’s wages for services performed in Connecticut are taxable regardless of the amount, unless a non-resident employee’s presence in Connecticut is ancillary to the primary duties performed outside of Connecticut.
Military pay received by members of the service stationed in Connecticut who are not residents of the state is not subject to Connecticut state income tax. Other sources of income in Connecticut would be subject to state tax. And a non-military spouse who is a not a resident of Connecticut and is in the state only to be with the spouse who is a military service member stationed there is not subject to Connecticut state tax on income for services performed in Connecticut.
If you are a nonresident or part-year resident of Connecticut and are required to file, you must use Form CT-1040NR/PY and also file Schedule CT-SI, Nonresident or Part-Year Resident Schedule of Income from Connecticut Sources. If you have a business with income inside and outside Connecticut, you must file Schedule CT-1040BA, Nonresident Business Apportionment.
The Connecticut Department of Revenue Services points out that if you are married and file a joint federal tax return, one spouse is a Connecticut resident and the other spouse is a non-resident, each spouse who is required to file a Connecticut return must file separately. You could choose to file jointly, but in that case you would both be subject to Connecticut tax on all your income from all sources as if you were both residents.
Connecticut Nonresident and Part-Year Resident Income Tax Return and Instructions, Connecticut Department of Revenue Services
Filing Requirements, Connecticut Department of Revenue Services
Form CT-1040NR/PY, Connecticut Nonresident and Part-Year Resident Income Tax Return
Nonresidents with Connecticut Source Income, Connecticut Department of Revenue Services
Schedule CT-1040BA, Nonresident Business Apportionment
Schedule CT-SI, Nonresident or Part-Year Resident Schedule of Income From Connecticut Sources