Connecticut Estimated Tax Payments Calculator

2026 rules

Enter your expected income to see what to send Connecticut and the IRS each quarter.

Your numbers

Filing status

Self-employment or business profit

W-2 wages

Other income (interest, dividends, gains, rental)

Connecticut tax withheld from paychecks

Last year's Connecticut tax (total on your return)

Leave at 0 to use this year's estimate only.

Federal tax withheld

Last year's federal tax (Form 1040 line 24)

Result

Connecticut quarterly payment$628

Projected federal tax (incl. SE tax)$17,147
Projected Connecticut tax$2,789
Connecticut amount to pay in estimates$2,510
Connecticut payment 1 · Apr 15, 2026$628
Connecticut payment 2 · Jun 15, 2026$628
Connecticut payment 3 · Sep 15, 2026$628
Connecticut payment 4 · Jan 15, 2027$628
Federal amount to pay in estimates$15,433
Federal payment · Apr 15, 2026$3,858
Federal payment · Jun 15, 2026$3,858
Federal payment · Sep 15, 2026$3,858
Federal payment · Jan 15, 2027$3,858
First payment, state and federal$4,486

Connecticut at a glance

Due dates: Apr 15, 2026, Jun 15, 2026, Sep 15, 2026, Jan 15, 2027
Rates: Connecticut taxes income at 7 rates from 2% to 6.99%.

Connecticut has "tax benefit recapture": at high incomes the lower brackets are phased out, so more of your income is taxed at the top rate than this estimate shows.

Connecticut tax brackets for 2026

Single (taxable income)
Rate	Taxable income
2%	$0 – $10,000
4.50%	$10,000 – $50,000
5.50%	$50,000 – $100,000
6%	$100,000 – $200,000
6.50%	$200,000 – $250,000
6.90%	$250,000 – $500,000
6.99%	over $500,000

Married filing jointly
Rate	Taxable income
2%	$0 – $20,000
4.50%	$20,000 – $100,000
5.50%	$100,000 – $200,000
6%	$200,000 – $400,000
6.50%	$400,000 – $500,000
6.90%	$500,000 – $1,000,000
6.99%	over $1,000,000

Questions

When are Connecticut estimated tax payments due for 2026?

Apr 15, 2026, Jun 15, 2026, Sep 15, 2026, Jan 15, 2027.

How much do I need to pay to avoid a penalty?

This calculator uses the federal safe harbor: 90% of this year's tax, or 100% of last year's (110% if your AGI is over $150,000), less withholding. A few states use a different share of the current year's tax, so check the Connecticut estimated-tax instructions too.