Connecticut Income Tax Calculator 2026

Why Connecticut's tax is more than its brackets

Connecticut has seven brackets from 2% to 6.99%, but it has no standard deduction, and the personal exemption and the lower brackets are both phased out as income rises. The result is a tax that behaves progressively in a way the bracket table alone doesn't show: a low earner pays almost nothing, while a single filer above about $200,000 gradually loses the benefit of the 2% and 4.5% brackets.

In order, the return works like this: start with federal AGI, apply Connecticut additions and subtractions to get Connecticut AGI, subtract the personal exemption (if any is left after the phase-out), apply the rates, add the phase-out and recapture amounts for higher incomes, then subtract the personal tax credit and other credits.

Social Security and pensions in Connecticut

Connecticut has steadily widened its retirement exclusions:

• Social Security is fully exempt if federal AGI is under $75,000 (single or married filing separately) or under $100,000 (married filing jointly, head of household or qualifying surviving spouse). Above those amounts it is partly exempt.
• Pension and annuity income (defined benefit plans, 401(k), 403(b), 457(b)) is fully subtracted when AGI is under $75,000 single or $100,000 joint, and partly subtracted up to $100,000 single or $150,000 joint.
• Traditional IRA distributions qualified for a 75% subtraction on 2025 returns, under the same income limits. Roth IRA distributions are not included.
• Half of Connecticut Teachers' Retirement System pay can be subtracted instead, and military retirement pay is exempt.

Connecticut credits worth checking

Three credits lower the bill for many residents:

• Property tax credit: up to $300 per return for property tax paid on your main home or a car (one car for single filers, two for joint filers), phased out as Connecticut AGI rises. Attach Schedule 3.
• Connecticut Earned Income Tax Credit: 40% of your federal EITC, plus an extra $250 if you have at least one qualifying child. It is refundable. Part-year residents and nonresidents do not qualify.
• Personal tax credit: a percentage reduction of tax, from 75% down to 1%, for lower incomes. It is built into the CT-W4 withholding tables and phases out completely at moderate incomes.

Filing your Connecticut return

Residents file Form CT-1040; nonresidents and part-year residents file Form CT-1040NR/PY and pay tax on Connecticut-source income. For 2026 income the return is due April 15, 2027 for most taxpayers. If the tax owed after withholding is $1,000 or more and you did not pay enough during the year, interest of 1% per month can apply, so people with large investment income often make estimated payments with Form CT-1040ES.

Connecticut has no local income taxes. Residents who work in New York or another state claim a credit for income tax paid to that state on the CT-1040, which usually eliminates double tax on the same wages.

Worked example: a retiree couple

Consider a married couple, both retired, filing a 2025 return with $40,000 of Social Security, a $30,000 pension and $10,000 of IRA withdrawals, giving federal AGI below $100,000. Connecticut lets them subtract all of the federally taxable Social Security, all of the pension and 75% of the IRA withdrawals ($7,500). Only $2,500 of IRA income remains, and with the joint personal exemption they owe no Connecticut income tax at all. The same income in a state without these subtractions could easily produce a four-figure bill.