IFTA Fuel Tax by State: How Rates Work and Why They Differ

Ask two owner-operators what they owe under IFTA and you'll get two very different answers, even if they drove the same number of miles. That's because IFTA fuel tax by state isn't one flat number. Every jurisdiction sets its own diesel tax rate, some add a surcharge on top, and the rate you owe changes every quarter. Understanding how these rates are built, and how they feed into your quarterly return, is the difference between a filing you trust and one you're guessing at.

This guide breaks down what an IFTA rate actually represents, why it moves every three months, how your net gallons owed gets calculated against it, and which factors push some states' rates far higher than others. We'll also walk through a real snapshot of rates across ten jurisdictions so you can see the spread for yourself.

What is an IFTA fuel tax rate, exactly?

IFTA (the International Fuel Tax Agreement) doesn't create a new tax. It's a reporting and clearing system that lets a carrier file one quarterly return with their base jurisdiction instead of registering separately in every state they drive through. The actual tax rate for each jurisdiction is still set independently by that state (or Canadian province), based on its own fuel excise tax laws.

When people talk about the "IFTA rate" for a state, they mean that jurisdiction's per-gallon diesel tax rate, published on the official IFTA, Inc. tax rate matrix and mirrored on each state's own motor fuel tax page. Some states also apply a separate surcharge on top of the base rate. Kentucky and Virginia both do this for diesel, and it's charged on every taxable gallon, not just gallons purchased in-state. Oregon is its own special case: it doesn't levy an IFTA fuel-use tax at all, using a weight-mile tax on registered vehicles instead.

It helps to separate two things that get mixed up a lot: your base jurisdiction and every other jurisdiction you drive through. You only register and file with one base jurisdiction, usually wherever your business is headquartered. But your quarterly return still accounts for every state and province you actually drove in, each at that state's own rate. IFTA doesn't average the rates or apply your home state's number everywhere. It calculates a separate net gallons figure for every single jurisdiction you touched that quarter, which is exactly why understanding how individual state rates differ matters even if you never file directly with most of those states.

Why do IFTA rates change every quarter?

Each of the 48 contiguous US states and 10 Canadian IFTA member provinces reviews and can adjust its own fuel tax rate on a quarterly cycle. Some states peg part of their rate to fuel price indexes or inflation formulas written into state law, which means the number can shift even when no one in the legislature voted on anything. Others only change rates once or twice a year but still get republished every quarter as part of the standard IFTA reporting cycle.

That's why a rate you used last quarter can be wrong this quarter. Carriers who keep an old spreadsheet of "state tax rates" and reuse it every filing are one of the most common sources of IFTA calculation errors. Before every return, pull the current quarter's numbers straight from iftach.org or your base jurisdiction's IFTA page, not from memory or an old file.

A real snapshot: how much IFTA rates vary by state

To show the actual spread, here's a snapshot of diesel rates across ten jurisdictions for the current quarter. Treat this as illustrative only. Rates are set independently by each state and change quarterly, so this table is a picture of one moment in time, not a number to file with.

Notice the spread: Oklahoma sits at roughly $0.19 a gallon while California runs to nearly $0.97, over five times higher. That gap alone can swing a multi-state quarter's tax bill by hundreds of dollars depending on where your miles fall. For the exact current-quarter number on any jurisdiction you run through, check its dedicated page, for example California's IFTA rate, Texas's IFTA rate, Kentucky's IFTA rate, or Virginia's IFTA rate, or verify directly at iftach.org or the relevant state Department of Revenue page.

Do all IFTA jurisdictions charge the same rate?

No, and the table above shows why. Every jurisdiction sets its own rate based on its own fuel excise tax policy, and there's no requirement for neighbouring states to align. A few things drive the differences you'll see quarter to quarter:

• State fuel excise tax policy: some states fund roads mainly through a high per-gallon diesel tax, others lean more on registration fees, tolls, or general revenue, which keeps their fuel tax lower.
• Added surcharges: Kentucky and Virginia both levy an extra per-gallon surcharge on top of the base diesel rate, owed on every taxable gallon reported that quarter.
• Indexing formulas: some states tie their rate to inflation or the price of fuel, so it moves automatically each year without new legislation.
• Alternative tax structures: Oregon skips an IFTA fuel-use tax altogether and instead charges registered vehicles a weight-mile tax, which is why its diesel rate for IFTA purposes reads as zero.
• Infrastructure spending priorities: states with large highway maintenance budgets or bigger deficits sometimes raise fuel tax rates faster than neighbouring states.

The rate itself is never the hard part. What trips carriers up is treating one quarter's numbers as permanent. We tell every fleet we onboard: pull fresh rates every single filing, because a state that held steady for two years can still move ten cents next quarter, says a compliance manager who processes multi-state IFTA returns for a regional carrier.

How the per-state rate feeds into your net gallons owed

The rate itself is only half the calculation. What you actually owe (or get refunded) in each jurisdiction depends on your net taxable gallons there, which compares fuel you burned in that state against fuel you bought in that state. Here's the sequence:

1. Work out your overall fleet fuel economy for the quarter: total miles driven divided by total gallons purchased, across all jurisdictions.
2. For each jurisdiction, calculate gallons consumed there: miles driven in that state divided by your overall MPG.
3. Subtract gallons actually purchased in that jurisdiction from gallons consumed there. A positive number is taxable gallons owed. A negative number is a credit.
4. Multiply net taxable gallons by that jurisdiction's current per-gallon rate (including any surcharge) to get the tax due or refund for that state.
5. Add up every jurisdiction. A net positive total means you pay your base state; a net negative total means you're due a refund.

A worked example

Say you drove 10,000 miles this quarter and bought 1,250 gallons of diesel in total, giving you an overall fuel economy of 8 miles per gallon. Of those 10,000 miles, 1,600 were driven in Kentucky, and you bought 150 gallons there. Gallons consumed in Kentucky: 1,600 divided by 8 equals 200. Net taxable gallons: 200 minus 150 equals 50 gallons owed. Using the effective Kentucky rate from the table above ($0.325 per gallon, base rate plus surcharge), that's 50 times $0.325, which comes to $16.25 owed to Kentucky for the quarter. Run the same steps for every jurisdiction you drove through and total them to get your quarterly return figure.

This is also why a high headline rate doesn't automatically mean a high bill. If you bought most of your fuel in a high-rate state, your net taxable gallons there could be low or even negative, earning you a credit rather than a charge. It's the balance between miles driven and gallons purchased, multiplied by that jurisdiction's rate, that actually determines what you owe.

If you want the mechanics without doing the arithmetic by hand each quarter, our full walkthrough on how to file IFTA covers the return process end to end, and getting your IFTA sticker and licence sorted is the prerequisite before any of this applies to you.

Which states should you watch most closely?

If your lanes regularly run through California, Pennsylvania, Illinois, Indiana, or Washington, you're operating in some of the highest per-gallon rate territory in the IFTA network, and even small differences between miles driven and gallons purchased there can move your bill meaningfully. If you run mostly through Oklahoma, Texas, or similarly low-rate states, the per-gallon exposure is smaller, but the calculation still matters for accuracy and audit readiness. Kentucky and Virginia deserve particular attention because their surcharge applies to every taxable gallon, not just fuel bought in-state, so it's easy to underestimate what's owed there if you forget to add it to the base rate.

Whichever states you run, the safest habit is the same: never assume last quarter's rate still applies. Confirm current numbers against the official IFTA tax matrix or your base jurisdiction's motor carrier page, and cross-check anything unusual against FMCSA guidance on qualifying vehicles if you're unsure whether a truck even falls under IFTA reporting.

It's also worth building the habit quarterly rather than scrambling the week a return is due. Pull the current rate matrix as soon as a new quarter opens, save a copy alongside your mileage and fuel records, and you'll have everything in one place when it's time to calculate net gallons owed. Carriers who leave rate-checking until filing day are the ones most likely to grab a stale figure by mistake, and an inflated or understated rate on even one jurisdiction can throw off your whole quarterly total.