You would need to mail your payment along with the Connecticut Form CT-1040V payment voucher. The payment voucher is included in your printed tax return. As an alternative, here is a link where you can print the voucher from the Connecticut Department of Revenue website http://www.ct.gov/drs/lib/drs/forms/1-2016/incometax/ct-1040v.pdf.
To ensure payment is applied to the correct account, write “2016 CT-1040V e-file” and your SSN(optional) on the front of the check.
Make check payable to Commissioner of Revenue Services
Mail the check to:
Department of Revenue Services
State of Connecticut
PO Box 2921 Hartford, CT 06104-2921