IFTA tax rates vary by state and quarter—Indiana's surcharge pushes the effective rate above $1.20/gallon in most quarters

IFTA base rates range from $0.11/gallon (Wyoming, Q4 2026) to $0.52/gallon (Washington, Q4 2026), but Indiana's consolidated rate of $0.61/gallon represents a merged surcharge that historically exceeded every other state's single rate.

Base IFTA rates span $0.11 to $0.52/gallon across all 49 jurisdictions

IFTA Inc. publishes the authoritative Tax Matrix before each quarter begins. Wyoming hits the floor at $0.11/gallon in Q4 2026; Washington claims the ceiling at $0.52/gallon in the same quarter. Most states reset their rates on January 1, April 1, July 1, and October 1, but Indiana, Kentucky, and Virginia use variable-rate formulas tied to wholesale fuel prices, meaning their rates can shift mid-quarter if the market moves enough.

The quarterly reset is statutory. If you're filing Q2 (April 1 through June 30), you use the rates that took effect April 1, not the ones from Q1. Miss that transition and you'll underpay one state and overpay another.

Indiana's $0.61/gallon rate is a consolidated surcharge that replaced a two-line filing structure

Indiana has held the highest-tax position for years. Indiana's current Special Fuel tax rate is $0.61 per gallon for the July 1, 2025 through June 30, 2026 period. That single number consolidates what was historically a base rate plus a separate Motor Carrier Fuel Tax surcharge, with the combined effective rate approximately $1.22/gallon.

This is not a tax cut; it's a reporting consolidation. Indiana folded the surcharge into the base rate itself starting Q2 2026. You no longer file a separate Schedule 2 surcharge line for Indiana. You calculate Indiana's tax on Schedule 1 at the merged rate. The effective burden remains unchanged; only the filing method shifted.

Four other states add surcharges on top of their base rates

Kentucky, Virginia, New York, and New Mexico maintain separate surcharges that sit on top of their base IFTA rates: Kentucky adds 2.0¢/gallon; Virginia adds 6.5¢/gallon; New York adds 0.95¢/gallon; New Mexico adds 1.0¢/gallon. These are reported independently on Schedule 2, not rolled into Schedule 1.

The critical trap: surcharges are calculated on gallons purchased in that state, not gallons consumed. If you purchased 100 gallons in Kentucky, you owe 2.0¢ per gallon in surcharge regardless of whether you actually consumed all 100 gallons there. Surcharges never generate credits, even if you bought more fuel than you burned. This is why surcharge calculations fail so often—drivers think about net gallons (miles divided by MPG) and forget that surcharges don't care about net consumption.

Worked example: A three-state route through Indiana, Ohio, and Kentucky in Q2 2026

You're an owner-operator running 4,400 miles in Q2 2026: 1,200 miles in Indiana, 1,600 in Ohio, 1,600 in Kentucky. You purchase 650 gallons total at an average of 6.77 MPG: 550 gallons in Indiana, 50 in Ohio, 50 in Kentucky.

Indiana's $0.61 rate on 550 gallons equals $335.50 in base tax. Ohio's $0.28 rate on 50 gallons equals $14.00. Kentucky's $0.26 base on 50 gallons is $13.00, and the 2.0¢ surcharge on 50 gallons is another $1.00, reported on Schedule 2. Your total quarterly IFTA liability is $363.50. The mistake most drivers make: they forget the Kentucky surcharge entirely, or they try to credit it against net gallons and end up calculating $0.00. Surcharges don't have nets; they're always owed.

Verify your rates before filing—one wrong rate triggers an audit and back-tax assessment

Using an outdated or incorrect rate is one of the fastest ways to trigger an audit adjustment. IFTA Inc. publishes the official Tax Matrix at iftach.org before each quarter begins. Your base jurisdiction's Department of Revenue also publishes current rates. Verify against primary sources, not from memory or old files.

If you underpay due to a rate error, you owe back taxes plus interest calculated from the original filing due date. A $10 underpayment on Indiana becomes $10 plus interest for the entire quarter you missed it. A $100 error across four quarters becomes $400 plus compounding interest. Owner-operators who file their own IFTA often hire a CPA to review the filing before submission—the cost of an error is always higher than the cost of verification.