Holiday Closing - The Department of Revenue Services will be closed on Monday, May 27th, a state holiday.

Software Developers


Software developers are required to successfully complete Assurance Testing System (ATS) tests for Modernized e-File (MeF). The purpose of ATS testing is to ensure that the software meets Connecticut specifications, the electronic returns have no validation or computation errors, and the returns can be transmitted in the correct format.

For MeF, DRS uses the State Exchange System (SES) to post schemas and test cases.  Software developers are granted access to the DRS’ folders on the SES site once DRS receives their completed annual Letter of Intent (LOI).  The annual LOI is made available on the SES site to all software companies who participated in MeF in the previous year.  If you are a new company looking to support Connecticut taxes via MeF, please contact the E-Commerce Unit at for assistance in obtaining a copy of the Letter of Intent.

For additional information regarding MeF or for filing withholding taxes through the FSET (Federal/State Employment Taxes) program, contact the Electronic Commerce Unit at 860-297-4973 or at

Paper Returns

DRS is in the process of migrating to a NEW Software Developer’s site.  To access the NEW site you must register by clicking on this link, Register for the NEW Software Developer’s Site, and follow the instructions.

If you already registered and received your acknowledgement email from DRS you may click on this link, Software Developer’s SharePoint Site