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Connecticut Income Taxes and CT State Tax Forms

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Prepare and efile Your Connecticut Tax Return

The tax software makes it easy for you to efile your state tax return and use the correct state tax forms. Prepare and efile your Connecticut state tax return (resident, nonresident, or part-year resident) and Federal tax return together or separately at View the federal tax return filing requirements.

Connecticut Income Tax Filing Deadline

The regular deadline to file a Connecticut state income tax return is April 15.

Tax Deadline Date Type of Income Tax Return Filing Deadline / Due Date Description
April 18, 2017 2016 Connecticut State Tax Return Due date for Connecticut State Income Tax Returns - income tax filing deadline
April 18, 2017 2016 Connecticut State Tax Extension Due date for Connecticut extensions
October 16, 2017 2016 Connecticut State Tax Return Last day to efile a 2016 Connecticut State Income Tax Return for tax extension filers and late efilers

View all state tax return filing deadlines.

Find federal income tax return filing deadlines.

Connecticut State Tax Forms that Can Be efiled supports all of the forms that Connecticut allows to be efiled. You can efile any of the following Connecticut state tax forms:

Form/Schedule Description Can I efile this form?
Form CT-1040 Income Tax Return    


Form CT-2210 Schedule B Interest Calculation for Underpayment Penality
Form CT-8822 Change of Address for Individuals
Form OP-186 Individual Use Tax Return
Schedule 1 Modifications to Federal AGI [Adjusted Gross Income]
Schedule 2 Taxes Paid to Another State Credit
Schedule 3 Property Tax Credit Worksheet
Schedule CT-EITC Earned Income Tax Credit

Connecticut State Tax Forms that Cannot Be efiled

Connecticut State Tax Withholding Form

Form Description
CT-W4 Employee's Withholding Certificate

CT Tax Extension

Extension Form Connecticut Extension Instructions How to File

CT-1040 EXT

If you did not file a federal tax extension, you must use Form CT-1040 EXT to request a 6-month extension to file your CT tax return (not pay taxes owed). This also extends your time to file your individual use tax return. You can do this if you have a good reason for your request. If you do not owe any additional tax and you filed an extension for your federal tax return, you are not required to file a CT state extension. The extended tax return due date is October 16, 2017.

If you filed a federal extension form and you expect to owe no additional CT income tax, you're not required to file the CT state extension form.

To avoid penalty and interest fees, your entire bill must be paid on or before the tax return deadline. Any remaining balance is generally subject to a 10% penalty. There will also be an interest charge of 1% per month of a fraction of month until payment is made. If you efile your CT return and you're mailing your tax payment (check only), complete and attach Form CT-1040V (Electronic Filing Payment Voucher) with your payment.

Complete and submit Form CT-1040 EXT (if no federal extension submitted)

Important Reminder! If you are efiling a Connecticut tax extension, you may need to efile a federal tax extension as well.

CT Tax Amendment

Connecticut state tax amendments can only be mailed; they cannot be efiled. Learn how to prepare and file an amended state Connecticut tax return.

Important Reminder! If you are filing a Connecticut tax amendment, you may need to file a federal tax amendment as well.

Connecticut 2015 Previous Year Tax Forms

Connecticut tax forms for past Tax Years cannot be prepared and efiled online. You will need to print, fill out, and mail the forms to the Connecticut Department of Revenue Service.
Form/Schedule Description How to File
Form CT-1040 Resident Income Tax Return

Download, complete, print out, sign, and mail

Form CT-1040ES Estimated Connecticut Income Tax Payment Coupon for Individuals
Form CT-1040V Electronic Filing Payment Voucher
Form CT-2210 Underpayment of Estimated Income Tax by Individuals, Trusts, and Estates (Schedules A & B)
Form CT-6251 Alternative Minimum Tax Return
Form CT-8822 Change of Address for Individuals
Form CT-8857 Request for Innocent Spouse Relief
Form OP-186 Individual Use Tax Return
Schedule 1 Modifications to Federal Adjusted Gross Income
Schedule 2 Credit for Income Taxes Paid to Qualifying Jurisdictions
Schedule 3 Property Tax Credit
Schedule CT-1040WH Connecticut Income Tax Withholding Supplemental Schedule

Where's My Refund? - Check Your Connecticut State Tax Refund Status

If you efile a Connecticut tax return, your refund will generally be processed within 4 business days. If you file your return on paper, allow 10-12 weeks after it has been processed by the CT Department of Revenue Services.

Check your Connecticut tax return refund status online.

CT efile Error Codes

If your Connecticut state return was rejected, you will receive an error reject code. If you prepared and efiled your return on, we will provide you with an explanation of how to correct the error on your return. You may then resubmit your state return at no additional charge until it is accepted by the state.

View a list of all Connecticut State efile Income Tax Return Error Reject Codes.

Connecticut Tax Facts

CT Income Tax:

Individual income is taxed across six tax brackets at six graduated tax rates:

  • 3% for the first $10,000 of taxable income
  • 5% for taxable income between $10,001 and $50,000
  • 5.5% for taxable income between $50,001 and $100,000
  • 6% for taxable income between $100,001 and $200,000
  • 6.5.% for taxable income between $200,001 and $250,000
  • 6.9% for taxable income $250,001 and $500,000
  • 6.99% for taxable income above $500,000

CT Sales Tax:

Connecticut has a state sales tax rate of 6.35% on the rental sale, lease, or rental of most goods. There is also a 7% luxury sales tax for the following purchases:

  • Most motor vehicles costing more than $50,000
  • Boats costing more than $100,000
  • Jewelry (real & imitation) costing more than $5,000
  • Apparel & footwear costing more than $1,000 (also applies to handbags, luggage, umbrellas, wallets, or watches costing more than $1,000)

More information on Connecticut Sales Tax

CT Sales Tax Holiday:

Connecticut has an annual one-week sales and use tax holiday. It usually occurs on the third week of August (from Sunday through Saturday). Certain items are exempt from Connecticut sales tax. However, the CT consumer will only receive the tax exemption if a specific total spending limit is met.

Refer to the chart below for Connecticut sales tax holidays for 2017.

Sales Tax Holiday Dates Sales Tax Holiday Items Included
August 20-26, 2017
  • Clothing and footwear: $100 or less

CT Personal Property Tax:

All personal property located within the state of Connecticut is taxable unless a statute specially exempts it. The tax varies based on each city and town in the state.

Odd Tax Fact:

The state of Connecticut has an online list of delinquent taxpayers.

CT State Tax Agency:

For more information, you can visit the website of The Connecticut Department of Revenue Services.

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