Please enter total miles driven.
Please enter total gallons purchased.
Enter miles for the state you want to calculate tax forPlease enter miles for the reporting state.
Tax-paid gallons at pump in this statePlease enter gallons purchased in state.
Find your state rate at ifta.org tax matrix. Common: TX=20, CA=85, FL=35, IL=47Please enter the state diesel tax rate.
IFTA Tax / Credit
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⚠️ Disclaimer: This calculator provides estimates based on the formula and tax rate you enter. Actual IFTA liability depends on official state rates for the filing quarter, surcharges (KY, VA, NY, NM), fuel type, and exempt miles. Always verify rates at the official IFTA Inc. tax matrix before filing.
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Sources & Methodology
Formulas and data verified against authoritative sources listed below.
IFTA Inc. — International Fuel Tax Association
iftach.org — Official IFTA Articles of Agreement, quarterly tax rate matrix, and member jurisdiction rules.
FMCSA — IFTA Requirements for Commercial Vehicles
fmcsa.dot.gov — Federal Motor Carrier Safety Administration IFTA qualification and filing requirements.
4-Step IFTA Formula:
1. Fleet MPG = Total Miles ÷ Total Gallons Purchased
2. Gallons Consumed (state) = State Miles ÷ Fleet MPG
3. Net Taxable Gallons = Gallons Consumed − Tax-Paid Gallons Purchased in State
4. Tax Owed = Net Taxable Gallons × State Rate (cents/gallon) ÷ 100
Positive result = tax owed to that state. Negative = credit from that state.
1. Fleet MPG = Total Miles ÷ Total Gallons Purchased
2. Gallons Consumed (state) = State Miles ÷ Fleet MPG
3. Net Taxable Gallons = Gallons Consumed − Tax-Paid Gallons Purchased in State
4. Tax Owed = Net Taxable Gallons × State Rate (cents/gallon) ÷ 100
Positive result = tax owed to that state. Negative = credit from that state.
Last reviewed: April 2026
How to Calculate IFTA Fuel Tax
IFTA (International Fuel Tax Agreement) simplifies fuel tax reporting for commercial carriers operating in multiple states. Instead of filing returns in each state separately, you file one quarterly return with your base state and IFTA redistributes taxes to the states you drove through. The calculation is based on how many gallons of fuel you consumed in each state — not where you bought the fuel.
The 4-Step IFTA Formula
Net Tax = (State Miles / Fleet MPG − State Gallons) × State Rate
Worked Example:
Total miles: 25,000 | Total gallons purchased: 3,472
Fleet MPG = 25,000 / 3,472 = 7.2 MPG
Texas miles: 8,000 | TX gallons purchased: 1,200 | TX diesel rate: 20.0 cents/gal
Gallons consumed in TX = 8,000 / 7.2 = 1,111 gallons
Net taxable gallons = 1,111 − 1,200 = −89 gallons (credit)
TX credit = −89 × $0.20 = −$17.80 credit
Total miles: 25,000 | Total gallons purchased: 3,472
Fleet MPG = 25,000 / 3,472 = 7.2 MPG
Texas miles: 8,000 | TX gallons purchased: 1,200 | TX diesel rate: 20.0 cents/gal
Gallons consumed in TX = 8,000 / 7.2 = 1,111 gallons
Net taxable gallons = 1,111 − 1,200 = −89 gallons (credit)
TX credit = −89 × $0.20 = −$17.80 credit
Common IFTA State Diesel Rates (Q2 2026)
| State | Diesel Rate (cents/gal) | Surcharge? | Notes |
|---|---|---|---|
| Texas | 20.0 cents | No | No surcharge |
| California | 85.0 cents | No | Highest rate in US |
| Florida | 35.2 cents | No | |
| Illinois | 47.4 cents | No | |
| New York | 17.4 cents | Yes | 0.95 cents surcharge |
| Pennsylvania | 72.5 cents | No | |
| Ohio | 47.0 cents | No | |
| Kentucky | 26.6 cents | Yes | 2.0 cents surcharge |
| Virginia | 28.5 cents | Yes | 6.5 cents surcharge |
| Oregon | 0 cents | N/A | Weight-mile tax, not fuel tax |
IFTA Filing Deadlines 2026
IFTA returns are due the last day of the month following each quarter: Q1 (Jan–Mar) is due April 30; Q2 (Apr–Jun) is due July 31; Q3 (Jul–Sep) is due October 31; Q4 (Oct–Dec) is due January 31. Even if you drove zero IFTA miles in a quarter, you must still file a zero-activity return or face the minimum $50 penalty.
What Triggers an IFTA Audit?
Common IFTA audit triggers include unrealistic MPG figures (above 9.0 or below 4.0 for diesel trucks), large credits in every state every quarter, missing fuel receipts for claimed purchases, and inconsistency between ELD mileage data and reported state miles. Maintain clean records for at least 4 years as required by IFTA regulations.
💡 Pro Tip: Buying fuel in low-tax states does not reduce your overall IFTA liability — it creates a credit in that state that offsets taxes owed elsewhere. Your tax liability is determined by where you drive, not where you fuel. Focus on accurate mileage records rather than fuel purchase strategy.
Frequently Asked Questions
IFTA is a fuel tax agreement covering 48 US states and 10 Canadian provinces. Commercial vehicles with two axles over 26,000 lbs gross vehicle weight, or three or more axles regardless of weight, that travel in two or more IFTA jurisdictions must have an IFTA license and file quarterly returns.
Step 1: Fleet MPG = Total Miles / Total Gallons. Step 2: State Consumed Gallons = State Miles / Fleet MPG. Step 3: Net Taxable Gallons = Consumed minus Tax-Paid Gallons in that state. Step 4: Tax = Net Taxable Gallons x State Rate. Repeat for every state and sum the results.
If your total credits across all states exceed your total tax owed, IFTA issues a net refund. You typically receive this from your base state within a few weeks of filing. Credits cannot be carried forward to the next quarter.
Q1 due April 30, Q2 due July 31, Q3 due October 31, Q4 due January 31. If the deadline falls on a weekend or holiday, it extends to the next business day. Always file even if you drove zero miles to avoid the minimum $50 penalty.
The penalty is $50 OR 10% of net tax liability, whichever is greater, plus 1% monthly interest on unpaid balances. If your IFTA license is revoked for non-filing, fines can reach $1,000 per day of non-compliance.
Alaska, Hawaii, and the District of Columbia are not IFTA jurisdictions. Miles driven there are non-IFTA miles reported separately on your return but not subject to IFTA tax.
Fleet MPG determines how many gallons you consumed in each state. Low MPG means more consumed gallons and more tax. High MPG means fewer consumed gallons. If your reported MPG seems unrealistic during an audit, it is a red flag. Typical diesel truck MPG is 5.5 to 8.0.
Kentucky (2.0 cents), Virginia (6.5 cents), New York (0.95 cents), and New Mexico (1.0 cent) impose surcharges in addition to their base IFTA diesel rate. Surcharges are calculated on total taxable gallons consumed, not net taxable gallons, so they are always owed even if you have a net credit in that state.
Maintain all fuel receipts showing date, location, fuel type, gallons, and price. Keep complete trip records showing odometer readings at state border crossings. ELD records, dispatch logs, and vehicle maintenance records should also be retained. IFTA requires 4 years of records.
Most modern ELD (Electronic Logging Device) providers include automatic IFTA jurisdiction mileage reports. The ELD uses GPS to track state crossings and calculates miles per jurisdiction automatically. You still need to manually add fuel purchase data in most cases.
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