DRS: Corporation What's New

Corporation Business Tax

What's New for 2016?


Information on e-filing Form CT-1120CU, Combined Unitary Corporation Business Tax Return


Beginning April 18, 2017, DRS will begin accepting Form CT-1120CU, Combined Unitary Corporation Business Tax Return, electronically for income year 2016.  Form CT-1120CU is only required to be filed by groups of companies (two or more C Corporations) with common ownership that are engaged in a unitary business.  Unless a group receives a waiver from the electronic filing requirement, it must file Form CT-1120CU electronically.        

For calendar year end filers, Form CT-1120CU is due by May 1, 2017. Check with your third party software company to determine when it will be ready to process and submit Form CT-1120CU. If you are not able to electronically file by the due date, request an extension by filing Form CT-1120 EXT, Application for Extension of Time to File Connecticut Corporation Business Tax Return. By requesting an extension, you will have six additional months to prepare and electronically file the return. The extension must be requested and the tax due must be fully paid by the original due date. Form CT-1120 EXT may be filed and payments may be made through our Taxpayer Service Center or through your third party software company.

For more information on combined unitary returns, see Special Notice 2016(1), Combined Unitary Legislation, and the instructions to Form CT-1120CU.

Office of Counsel Guidance, OCG-3, Combined Unitary Frequently Asked Questions.

Tax Reform

Connecticut has recently enacted significant reforms to its Corporation Business Tax. Among the changes are:

Combined Unitary Reporting: All corporations that are engaged in a singular business enterprise will now be treated and taxed as a single business. This eliminates a common tax strategy employed by sophisticated, multistate corporations and puts all corporations on equal footing.

Reference SN 2016(1), Combined Unitary Legislation for more information.

Single Sales Factor Apportionment: Corporations and other business entities will generally determine the percentage of their income subject to tax based solely upon the percentage of their Connecticut sales. Previously, most businesses were required to include the percentage of their Connecticut property and payroll in the apportionment calculation.

Market Based Sourcing: Previously sales of services and most intangible property were considered to be made at the location of the seller. These sales will now be considered to be made where the customer is located. As a result, the sourcing rules governing receipts from tangible property, services and intangibles are consistent.

Due Date Change

Your Connecticut return is due on the first day of the month following the due date of the federal return. Because of a change in the federal due date, the due date of the Connecticut return has changed. Beginning with the 2016 return, the due date generally will be the first day of the fifth month after the end of your corporation’s year. For example, if your corporation has a December 31st year end, the return is now due on May 1st.

Exception for June 30th year ends: If your corporation has a June 30th year end, the return is due on October 1st.

More Information

Forms & Instructions




Regulations of Connecticut State Agencies


General Statutes of Connecticut (revised to January 1, 2015)


2016 Supplement to the General Statutes of Connecticut


File & Pay (TSC)


Voluntary Disclosures

Frequently Asked Questions

Filing Requirements

Due Dates & Extensions



E-File Issues

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CT Secretary of the State


CT Department of Labor


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Content Last Modified on 7/18/2017 3:34:54 PM