IFTA taxes range from $0.19/gallon in Oklahoma to $1.22/gallon in Indiana when surcharges are included—here's what you actually owe per quarter

Your quarterly IFTA tax bill is the sum of (gallons consumed in each state × that state's fuel-tax rate) minus fuel taxes already paid at the pump. Indiana's effective rate of $1.22/gallon is now the highest; Oklahoma's $0.19/gallon is the lowest. Variable-rate states like Kentucky and Virginia can shift mid-quarter if wholesale prices move.

Indiana's $1.22/gallon consolidated surcharge takes effect Q2 2026

Indiana folded its Motor Carrier Fuel Tax surcharge into a single Special Fuel tax of $0.63/gallon, effective July 1, 2025–June 30, 2026. This eliminates the separate Schedule 2 filing that trapped carriers for years. If you were tracking surcharge separately before, stop—it's all one number on your IFTA return now.

Oklahoma at $0.19/gallon and California at $0.971/gallon mark the extremes

Oklahoma's $0.19/gallon is the lowest IFTA rate nationwide. A driver running 10,000 miles at 6.5 MPG in Oklahoma burns roughly 1,538 gallons and owes about $292 in raw IFTA tax. The same run in California costs $1,493 because California charges $0.971/gallon—a five-fold spread that determines which lanes pencil out. Oregon shows zero IFTA rate but requires a weight-mile tax instead, so you cannot avoid tax by routing through Oregon.

Kentucky, Virginia, and New Mexico add surcharges on top of base rates

Kentucky adds 2.0¢/gallon; Virginia adds 6.5¢/gallon; New Mexico adds 1.0¢/gallon. These appear as separate line items on Schedule 2 of your IFTA return. The critical trap: surcharges apply to gallons purchased in that state, not consumed. If you buy 500 gallons in Virginia, you owe $32.50 surcharge (6.5¢ × 500) whether you burn all 500 in Virginia or only 400. Surcharges generate zero tax-paid credit—they always cost money and cannot be offset by fuel taxes paid elsewhere.

Worked example: Q2 run across four states shows why rates add $300+ to quarterly liability

A carrier runs 8,400 miles in Q2 2026 at 6.0 MPG fleet average, burning 1,400 gallons total.

The Kentucky surcharge applies only if you purchased fuel in Kentucky. If you bought 350 gallons in Texas and burned them in Kentucky, surcharge is zero. Net liability after fuel taxes already paid at the pump typically runs $400–$500. The same 8,400 miles run entirely in Oklahoma would owe roughly $266 base IFTA; entirely in Indiana would owe roughly $868—more than triple.

Variable-rate states shift quarterly or mid-quarter when wholesale diesel prices cross thresholds

Indiana, Kentucky, and Virginia tie rates to wholesale diesel prices, so Q3 rates differ from Q2 even within one year. Some recalculate mid-quarter if prices move enough. Monitor the IFTA Inc. official rate matrix and each state's DOR website before filing. Using outdated rates triggers audits, back taxes, interest, and penalties. Always cross-check rates at IFTA Inc. against each state's DOR surcharge amounts before submission.

Tax-paid credits from fuel receipts can zero out or reverse your liability

IFTA tax owed = (gallons consumed in each state × that state's rate) minus (fuel taxes paid at the pump in that state). A carrier who buys 300 gallons in Texas at $0.20/gallon IFTA rate pays $60 at the pump but consumes only 250 gallons in Texas—resulting in a $10 credit. Credits that exceed your quarterly liability carry forward to the next quarter. Underpaying triggers back taxes plus 8% annual interest plus a $50 minimum penalty or 10% of net tax owed, whichever is larger.