Connecticut Estimated Tax Payments

Does Connecticut require estimated tax payments?

Yes. Connecticut requires quarterly estimated tax payments for taxpayers who expect to owe state income tax during the year. This applies to individual, Sole Proprietorship, C Corporation. If your expected tax liability exceeds the state's minimum threshold after accounting for withholding and credits, you are generally required to make estimated payments. Failure to pay estimated taxes can result in underpayment penalties and interest charges from Connecticut Department of Revenue Services.

When are Connecticut estimated tax payments due in 2026?

Connecticut estimated tax payments for 2026 are due on the following dates: Apr 15, 2026, Jun 15, 2026, Sep 15, 2026, Jan 15, 2027. These quarterly payments cover income earned during each respective period. The first payment (Q1) covers January through March, Q2 covers April through May, Q3 covers June through August, and Q4 covers September through December. If a due date falls on a weekend or holiday, the payment is due the next business day.

What happens if I miss an estimated tax payment in Connecticut?

If you miss an estimated tax payment in Connecticut, you may be subject to an underpayment penalty. Connecticut Department of Revenue Services calculates this penalty based on the amount of underpayment, the period of underpayment, and the applicable interest rate. The penalty is typically assessed on Form Form CT-1040 when you file your annual return. To avoid penalties, ensure each quarterly payment meets the required threshold — generally the lesser of 90% of the current year's tax or 100% of the prior year's tax (110% for higher-income taxpayers).

How do I calculate Connecticut estimated tax payments?

To calculate your Connecticut estimated tax payments: (1) Estimate your total expected Connecticut taxable income for 2026. (2) Calculate the tax owed using current Connecticut tax rates and brackets. (3) Subtract any expected withholding and credits. (4) Divide the remaining amount by four for equal quarterly payments. Alternatively, you can use the annualized income installment method if your income is not evenly distributed throughout the year. Visit Connecticut Department of Revenue Services at https://portal.ct.gov/DRS for official worksheets and calculators.

Are Connecticut estimated payment dates the same as federal?

Yes, Connecticut follows the same quarterly schedule as the federal government for most entity types. This makes it convenient to submit both federal and state estimated payments at the same time.

What form do I use for Connecticut estimated payments?

Connecticut has its own estimated payment voucher form. Contact Connecticut Department of Revenue Services at https://portal.ct.gov/DRS for the correct form, instructions, and electronic payment options. Many states now offer online portals for making estimated payments directly.