IFTA Fuel Tax Calculator
Estimate your IFTA fuel tax liability or credit for a given state based on miles driven and gallons purchased.
Results
Visualization
How It Works
IFTA collapses what would be 48 separate state fuel-tax filings into one quarterly return administered by your base jurisdiction. You pay tax at the pump in whichever state you fill up; the IFTA return reconciles that against where you actually burned the fuel (miles divided by fleet MPG). High-tax states where you drove but didn't fill = you owe more. Low-tax states where you topped off = you generate credits. The 2026 rate spread is wide: Pennsylvania sits at $0.787/gal (highest in the lower 48 — combined excise + Oil Company Franchise Tax), Indiana at $0.594/gal, Texas at $0.20/gal, Oklahoma at $0.20/gal, Mississippi at $0.184/gal (lowest after Alaska). Burning 50 gallons in PA without buying any costs you about $39 in IFTA tax. Get the math wrong and the audit penalty stacks up fast.
The Formula
Variables
- Miles Driven — Quarterly miles within the jurisdiction — must match ELD/GPS data
- Fleet MPG — Quarterly average from total miles divided by total gallons across all states
- State Tax Rate — Posted IFTA rate for the quarter (Q1 2026 examples below)
- Gallons Purchased — Tax-paid retail diesel inside the state, by receipt
Worked Example
Q1 2026 trip log: 3,000 miles driven in Texas (rate $0.20/gal), 500 gallons purchased in Texas. Fleet MPG that quarter ran 6.5. Consumption in TX = 3,000 / 6.5 = 461.5 gallons. Tax owed on consumption: 461.5 x $0.20 = $92.31. Tax already paid at TX pumps: 500 x $0.20 = $100.00. Net = $7.69 TX credit. Now contrast with the same 3,000 miles run in Pennsylvania at $0.787/gal but only 200 gallons bought there: tax owed 461.5 x $0.787 = $363.20, tax paid 200 x $0.787 = $157.40, net $205.80 owed to PA — wired through the IFTA clearinghouse to PennDOT. The credits and debits offset on the single return your base state collects.
Practical Tips
- Q1 2026 tax-rate cheat sheet for routing: PA $0.787, CA $0.882 (incl. clear-diesel components), IN $0.594, IL $0.668, OH $0.470, NY $0.4525, TX $0.20, OK $0.20, MS $0.184, MO $0.27. Fill up in low-rate states adjacent to high-rate corridors when timing allows — PA-bound from OH, top off in Ohio.
- Match every receipt to your ELD trace by date and odometer. Most state IFTA auditors (per IFTA Audit Manual P1110) cross-check fuel receipts against the ELD GPS pings and will reject receipts that don't reconcile to a logged stop within a 1-hour window.
- Filing deadlines: April 30, July 31, October 31, January 31. Late filing penalty is the greater of $50 or 10% of net tax due, plus 1% per month interest. Miss two consecutive quarters and your IFTA license can be revoked, which means you can't legally cross state lines until you reinstate.
- Under-the-hood gallons (refilling a sealed reefer tank, idling on auxiliary fuel) are NOT IFTA-deductible because they don't move the truck. Only diesel pulled from your sealed truck tank counts toward miles. Some carriers wrongly include reefer gallons and trigger audit assessments.
- Keep records 4 years (IFTA Articles of Agreement R1230). Receipts must show date, seller, full address (city + state), product type, gallons, price/gallon, total, and your unit number or driver name. A receipt missing any of these is rejectable in audit.
- Inflated fleet MPG = under-reported consumption = under-paid tax. If your reported MPG averages 7.5 but your actual fill-to-fill is 6.4, an audit will recalculate at the lower MPG and add 12-15% in back tax plus penalties. File the real number.
Frequently Asked Questions
Who has to file IFTA?
IFTA covers any qualified motor vehicle: 2+ axles with GVW over 26,000 lbs, OR 3+ axles regardless of weight, OR any combination exceeding 26,000 lbs combined. The vehicle must travel in 2+ IFTA member jurisdictions (the lower 48 plus 10 Canadian provinces). Single-state operators don't file IFTA.
When are IFTA returns due in 2026?
Q1 (Jan-Mar) due April 30, 2026. Q2 (Apr-Jun) due July 31. Q3 (Jul-Sep) due October 31. Q4 (Oct-Dec) due January 31, 2027. Most base jurisdictions accept e-filing; Texas Comptroller and California CDTFA both have online portals that auto-calc the rates.
What records does an IFTA audit actually examine?
Auditors pull a sample quarter and examine: every fuel receipt (must show all required fields), driver trip sheets or ELD logs showing distance per jurisdiction, odometer readings beginning/end of quarter, and bulk fuel withdrawal records if you have an on-site tank. Per IFTA Audit Manual A560, inadequate records mean recalculation at 4.0 MPG worst-case, which roughly doubles your tax bill.
Can I actually get a refund check from IFTA?
Yes — net credits over $10 are refunded by your base jurisdiction (some, like Texas, hold credits to offset future quarters unless you specifically request a refund). If you systematically buy fuel in OK or TX while running miles in PA or CA, the math works against you and you owe net. The opposite pattern produces refunds.
Do I need IFTA for a single-state local hauler?
No. IFTA only triggers when you cross into a second IFTA jurisdiction. If you stay inside Texas with a Texas-based truck, you pay Texas fuel tax at the pump and that's the end of it — no quarterly filing. The moment you cross into Louisiana with a load, you need an IFTA license or a 72-hour temporary trip permit.
How do I handle a quarter with zero miles?
You still file a "zero return" — the IFTA agreement requires a return every quarter you hold an active license, even if the truck didn't move. Skipping creates a non-filer flag and triggers an automatic late penalty. E-file portals let you submit zero returns in under two minutes.