Connecticut Fuel Tax Filing Requirements Are Changing: Form OP-216, Form O-MF, Form MF-1

Connecticut fuel companies face two compliance deadlines arriving simultaneously this summer. Effective July 31, 2026, all motor fuel tax returns must be filed electronically through myconneCT, and payments must be made electronically as well. The Connecticut Department of Revenue Services (DRS) stopped mailing paper returns effective July 1, 2026.

On that same date, Connecticut’s motor vehicle fuels tax rate on diesel increases to 49.9 cents per gallon, effective through June 30, 2027.

For fuel tax teams, these changes increase the need for standardized data, consistent review processes, and reliable filing documentation before return information enters myconneCT.

What Is Changing

Beginning with returns due after July 31, 2026, Connecticut taxpayers must file electronically through myconneCT. Taxpayers will log in, navigate to the applicable tax account and filing period, and file or amend the return directly in the system.

For Special Fuel, Motor Vehicle Fuels, and Tax-Paid Motor Vehicle Fuel tax types, taxpayers complete the applicable returns electronically by entering return information through myconneCT and uploading required schedules where applicable. Impacted forms include:

• Form OP-216, Special Fuel Tax Return
• Form O-MF, Motor Vehicle Fuels Tax Return
• Form MF-1, Tax-Paid Motor Vehicle Fuel Tax Return

Connecticut DRS has also announced the motor vehicle fuels tax rate on diesel will be 49.9 cents per gallon from July 1, 2026, through June 30, 2027. The rate is calculated annually by the Commissioner of Revenue Services under a formula prescribed by Connecticut General Statutes Section 12-458h.

Who Is Impacted

These changes are most relevant for any organization responsible for Connecticut fuel tax reporting. That includes:

• Fuel distributors and wholesalers
• Suppliers and terminal operators
• Retail fuel operators
• Companies claiming Connecticut fuel tax refunds
• Tax teams preparing, reviewing, or amending Connecticut fuel tax filings

More specifically:

• Form OP-216 applies to distributors handling special fuels: diesel, propane, natural gas, jet fuel, and kerosene. Returns are due monthly by the 25th of the following month.
• Form O-MF to distributors handling gasoline, gasohol, and aviation gas. Returns are also due monthly by the 25th of the following month.
• Form MF-1 applies to distributors reporting motor vehicle fuels on which Connecticut excise tax was already paid at the point of purchase.

The change is especially significant for companies still relying on paper returns, spreadsheet-based workbooks, manually created CSV files, or decentralized filing processes managed by different individuals across the organization.

How IGEN Handles Connecticut E-Filing

Connecticut’s move to mandatory electronic filing through myconneCT is a process change, not just a portal change. The data that goes into the system determines the outcome. IGEN Tax Reporting is built to own that process from the start.

IGEN’s e-file workflow includes that filers upload transaction data into IGEN, assign transactions to the applicable schedules and line items, and generate a validated, signature-ready return. For jurisdictions that allow direct submission, including Connecticut through myconneCT, IGEN generates and submits the e-file from within the platform. Filers don’t build CSV files from scratch or manually enter line items into a state portal.

The workflow eliminates the manual handoff that creates most filing errors: data leaves IGEN in the format the state requires, not in whatever format an individual preparer happened to use that month.

For Connecticut filers, that means:

• Transaction data is uploaded once and assigned to the correct schedules inside IGEN
• Signature-ready returns are generated from validated data, not manually assembled spreadsheets
• Every transaction is traceable from its source through to its presentation on the return — critical when a return is audited or needs to be amended
• Rate changes, form revisions, and filing requirement updates are maintained within IGEN’s regulatory intelligence library, so compliance teams aren’t monitoring DRS announcements to stay current

The operational benefit of removing manual preparation steps is direct: fewer errors, fewer amendments, and less time spent on rework that doesn’t produce revenue.

Connecticut’s electronic filing mandate removes paper as an option. It does not remove the risk of inaccurate data, but IGEN does.

This analysis is intended for informational purposes only and is not tax advice.  For tax advice, consult your tax adviser. See the full disclaimer here.