Connecticut IFTA fuel tax rate – Q4 2026
Connecticut (CT) taxes diesel at $0.499 per gallon for October–December 2026. The Q4 2026 return is due January 31, 2027.
| Fuel type | Rate $/gal | Credit at the pump |
|---|---|---|
| Diesel (special diesel / ULSD) | $0.499 | Yes |
Rates from the IFTA, Inc. tax rate matrix (iftach.org); verify on iftach.org before filing. The Q4 2026 matrix can still be revised until December 4, 2026.
Connecticut diesel rate by quarter
Every quarter loaded here, newest first. Use the quarter you are filing for, not the current one.
| Quarter | Diesel $/gal | Change |
|---|---|---|
| Q4 2026 October–December 2026 | $0.499 | no change |
| Q3 2026 July–September 2026 | $0.499 | up $0.01 |
| Q2 2026 April–June 2026 | $0.489 | no change |
| Q1 2026 January–March 2026 | $0.489 | — |
How the Connecticut rate is used on your IFTA return
For each state the return takes the miles you drove there, divides by your fleet MPG to get taxable gallons, multiplies by the state rate, then subtracts the tax you already paid on gallons bought in that state. With the Q4 2026 Connecticut rate:
- 10,000 miles in Connecticut ÷ 6.5 MPG = 1,538 taxable gallons
- 1,538 gal × $0.499 = $767.46 tax
- 1,000 gal bought in Connecticut × $0.499 = $499.00 credit
- Net for Connecticut: $268.46 owed
Your base state nets every state’s line into one payment or refund. This is a reference, not filing advice; verify with your base jurisdiction.
Connecticut IFTA questions
What is the Connecticut IFTA diesel tax rate for Q4 2026?
$0.499 per gallon of diesel for October–December 2026. The Q4 2026 return is due January 31, 2027.
Does Connecticut charge an IFTA surcharge?
No. Connecticut has a single diesel rate of $0.499 per gallon and no surcharge line on the IFTA return. Only Kentucky and Virginia charge a surcharge.
Did the Connecticut diesel rate change from Q3 2026 to Q4 2026?
No. The Connecticut rate stayed at $0.499 per gallon from Q3 2026 to Q4 2026.
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