Beginning with tax year 2014, Connecticut requires all Forms CT-1065/CT-1120SI, their extensions, and their associated payments to be filed and paid electronically.
Per the Connecticut Pass-Through Entity Tax Instructions:
"Form CT-1065/CT-1120SI, Connecticut Pass‑Through
Entity Tax Return, must be filed electronically and
payments must be made electronically.
If the PE can show that filing and paying
electronically creates an undue hardship, DRS
may grant a one-year waiver of the electronic
filing and payment requirement. Request a
waiver by completing Form DRS-EWVR,
Electronic Filing and Payment Waiver Request,
no fewer than 30 days before the due date of your
first electronic filing and payment. See Policy
Statement 2011(3), Requests for Waiver of Electronic
Filing and Electronic Payment Requirements"
Form DRS-EWVR can be produced by completing the CT screen EWVR, located on the CT Other tab.