IFTA Fuel Tax Calculator for Truckers

The International Fuel Tax Agreement (IFTA) lets a motor carrier file one quarterly fuel tax return with its home ("base") jurisdiction instead of separate returns in every state and province it drives through. The tax follows the miles: each jurisdiction gets tax on the fuel your trucks burned there, based on your fleet's average miles per gallon, and you get credit for the tax you already paid at the pump.

How to use this calculator: enter your total IFTA miles and total gallons for the quarter, then each jurisdiction's miles and its current diesel rate in cents per gallon. The calculator returns your fleet MPG, taxable gallons by jurisdiction, and the gross tax due in each.

The calculator is for informational purposes only. It produces an estimate of gross tax by jurisdiction; it doesn't file your return, look up rates, or apply surcharges, credits, penalties, or interest for you.

What the calculator computes — and the one step you do yourself

1. Fleet MPG = total miles ÷ total gallons (all qualified vehicles, all jurisdictions, including non-IFTA miles).
2. Taxable gallons in each jurisdiction = your total gallons × (that jurisdiction's miles ÷ total miles). This is the same as jurisdiction miles ÷ fleet MPG.
3. Gross tax due in each jurisdiction = taxable gallons × rate.

On the actual return, a fourth step nets out what you've already paid:

4. Net tax = gross tax due − (tax-paid gallons bought in that jurisdiction × rate).

The calculator stops at step 3, so subtract your tax-paid purchases afterward. A positive net is owed to that jurisdiction; a negative net is a credit that offsets what you owe elsewhere.

Inputs, field by field

Total miles. Every mile your qualified vehicles traveled in the quarter, including miles in non-member areas (Alaska, Hawaii, the territories) and on toll roads. Use odometer, hubodometer, or ECM/GPS distance — the same source your trip records use.

Total gallons. All fuel of this type placed in the vehicles' supply tanks during the quarter, wherever bought: retail fuel, bulk fuel from your own tank, and fuel bought in non-IFTA areas. Report diesel and gasoline separately; run the calculator once per fuel type.

Jurisdiction name, miles, rate. Enter the miles driven in each state or province. For the rate, use the IFTA tax rate matrix for the quarter you're filing, in cents per gallon. The calculator has three jurisdiction rows; for a longer route, run it in batches with the same totals and add the results.

Current IFTA diesel rates for common jurisdictions

These special diesel rates are from the final 3Q 2026 IFTA tax rate matrix. The 4Q 2026 matrix posted so far shows the same rates for these jurisdictions, but it isn't final until December 4, 2026, so check it before you file the fourth quarter.

Oregon has no IFTA diesel rate because it taxes heavy trucks by weight and miles instead; you still report Oregon miles on the IFTA return. Canadian provinces are published per liter in Canadian dollars and converted at each quarter's exchange rate.

Several of these rates changed during the past year — California, Mississippi, Virginia, and Washington in the third quarter of 2026 alone — so always pull the matrix for the specific quarter you're filing.

Worked example: one truck, three states

A single-truck carrier based in Texas runs this quarter:

• Total miles: 30,000
• Total gallons: 5,000 → fleet MPG = 30,000 ÷ 5,000 = 6.0

That $1,145.00 is what the calculator shows. Now the step you do yourself — credit for tax-paid fuel:

The carrier owes $169.00 with the return: $491.67 to Missouri, offset by $322.67 of credits from Texas and Oklahoma. The base jurisdiction (Texas) collects the net and distributes it.

Notice that the total fuel tax for the quarter — $1,145 — depends only on where the truck drove, not where it fueled. Buying fuel in a low-tax state lowers the pump price, but the IFTA return charges the difference back to the states where you drove.

Surcharge jurisdictions

Kentucky and Virginia add a diesel surcharge that's collected only through IFTA. For those two, compute the surcharge separately: taxable gallons × surcharge rate, with no credit for fuel bought there. For 5,000 Kentucky miles at 6.0 MPG: 833.33 gallons × $0.1050 = $87.50 of surcharge on top of the regular Kentucky tax.

How to read your result

• Fleet MPG that jumps from your usual range — say, 6.4 last quarter and 8.9 this quarter — usually means missing fuel receipts or overstated miles. Auditors compare quarters, so fix the records before you file.
• A large positive balance means you fueled mostly in states you drove through briefly. That's not wrong, just a cash-flow timing issue.
• A net credit across all jurisdictions is refunded or carried forward by your base jurisdiction under its procedures.

Common input mistakes

1. Leaving out non-IFTA miles or bulk fuel. Both totals must include everything; dropping either one changes fleet MPG and shifts tax between states.
2. Entering dollars instead of cents. Typing 0.979 for California instead of 97.9 understates the tax by a factor of 100.
3. Using last quarter's matrix. Rates change; Mississippi went from $0.21 to $0.24 per gallon between 2Q and 3Q 2026.
4. Counting fuel bought for a reefer unit or other off-road equipment. Fuel that doesn't go into the qualified vehicle's supply tank is not reported as vehicle fuel; keep those receipts separate.
5. Rounding MPG too early. Carry fleet MPG to at least two decimals. On 30,000 miles, the difference between 6.0 and 6.04 MPG is about 33 gallons.
6. Mixing fuel types. Diesel, gasoline, and alternative fuels each have their own rates and their own lines on the return.

Filing deadlines and penalties

Returns are due the last day of the month after each quarter. Under IFTA's rules, a due date falling on a weekend or legal holiday moves to the next business day:

Late filing or underpayment costs the greater of $50 or 10% of the delinquent tax, plus interest. For U.S. carriers, IFTA interest for 2026 is 9% a year (0.75% a month), set at the IRS underpayment rate plus two points (IFTA interest rates). You must file every quarter, even with zero miles.

Records that make the numbers stick

IFTA's Procedures Manual requires you to keep distance and fuel records for four years from the due date or filing date, whichever is later. If an auditor finds your records inadequate, the jurisdiction can cut your reported MPG by 20% or assign 4.00 MPG — which raises taxable gallons everywhere you drove. At 4.00 MPG instead of 6.0, the example above would have 7,500 taxable gallons instead of 5,000.

For the full picture — who must register, how to choose a base jurisdiction, decal rules, audits, and the separate weight-distance taxes in Oregon, Kentucky, New Mexico, and New York — read the IFTA tax guide for truckers. Owner-operators should also fold IFTA payments into their business tax planning: fuel tax is part of your deductible fuel cost on Schedule C, and the guide to paying quarterly estimated taxes covers the income-tax side. A new tractor bought this year can usually be written off with 100% bonus depreciation; the MACRS depreciation calculator shows the schedule for 3-year over-the-road tractor units.