Idaho State Tax Commission

Idaho State Tax Commission

IFTA Licensees

For more information on trucking in Idaho, see and IFTA, Inc.

You can save time and postage by e-filing your IFTA returns and payments. You can also apply for your IFTA license, complete your annual license renewal, and reorder decals — all online.


The information in this section applies only to Idaho IFTA licensees, unless otherwise noted. There are two ways to file your IFTA Return (Form 3150). You can file a paper return or use free electronic filing to help you calculate your IFTA return online.

Preparing Idaho's IFTA return (Form 3150)

There are five steps you can follow to ensure that you're filing your IFTA return correctly. If you've kept the proper records (see recordkeeping), your Idaho IFTA return will be much easier to file. Note: These steps are shown on a sample IFTA return.

Average fleet miles per gallon

Step 1: Compute your average fleet miles per gallon (MPG) for travel in all jurisdictions during the tax period for each fuel type you're reporting. The miles traveled must include every mile traveled by every IFTA fleet vehicle using that fuel type, including off-highway miles, miles traveled under a temporary fuels tax permit, and nonrevenue (deadhead, bobtail) miles. Divide these miles by the total gallons of fuel put into the supply tanks of these same vehicles during the period. It doesn't matter whether the fuel was tax-paid, or whether some of the fuel will be used to run auxiliary equipment; you must include all of the fuel in this calculation.

Jurisdiction tax calculation

Step 2: Report total miles traveled inside each jurisdiction's boundaries for each fuel type. Include every mile your fleet traveled in the jurisdiction (e.g. on-highway, off-highway, temporary permit, etc.).

Step 3: Report taxable miles for each fuel type. Most jurisdictions don't have distance exemptions, so your total miles will equal your taxable miles in most circumstances.

In Idaho, nontaxable miles include miles traveled under a temporary permit for fuels tax and off-highway miles. Each jurisdiction with distance exemptions will have its own definition of nontaxable miles. You must document nontaxable miles in order to claim them on your IFTA return for the jurisdictions which exempt these miles. For example, you must report off-highway miles separately from on-highway miles on your detailed Individual Vehicle Mileage and Fuel Report (IVMR) and monthly and quarterly summaries. You must include nontaxable miles in your total miles when computing your MPG, and in each jurisdiction's total miles column.

If you operate in multiple jurisdictions, you should contact each jurisdiction or check the IFTA Web site to determine which jurisdictions have distance exemptions and to get a definition of their nontaxable miles. In Idaho, the fuels tax applies only to fuel consumed on Idaho highways. If you've determined that you're eligible for nontaxable miles in a particular jurisdiction, subtract the nontaxable miles from total miles to get the taxable miles in each jurisdiction.

Step 4: Compute taxable gallons of each fuel type consumed for each jurisdiction. Divide the taxable miles you determined for each jurisdiction in Step 3 by the average fleet MPG you computed in Step 1.

Step 5: Total the tax-paid gallons* for each jurisdiction. These are gallons of fuel placed into the supply tanks of your fleet vehicles that had the jurisdiction's fuel taxes included in the purchase price. You must have receipts to support these totals.

* When motor fuel is purchased from an Indian-owned retail outlet in Idaho after December 1, 2007, the purchase price may not include the Idaho motor fuels tax and may not qualify as an Idaho tax-paid purchase, unless authorized in an agreement between the state and a specific tribe (Idaho Code sections 63-2444 or 67-4002). See Untaxed Fuel Purchased on Idaho Indian Reservations on our Web site, or contact us.


Some jurisdictions charge a fee (called a surcharge) in addition to the fuel use tax. The surcharge jurisdictions (and their respective surcharge rates) are identified on the IFTA fuel taxes rate chart, which is mailed to you each quarter.

To report the surcharge on your IFTA return (Form 3150), enter a second reporting line for that jurisdiction directly below the line where you reported its fuel use tax.

  • Enter the surcharge rate in the column titled Tax Rate.
  • Enter the same total miles, taxable miles, and taxable gallons you entered on the previous line.
  • Since the surcharge isn't included in the amount you paid for the fuel, you can't claim any "surcharge" tax-paid gallons. Enter "zero" in the column for Tax-Paid Gallons.
  • Net Taxable Gallons will be the same as the figure for Taxable Gallons.
  • Multiply the number in the Net Taxable Gallons column by the surcharge rate. Enter the surcharge amount you compute in the Tax Due/Refund column.

Leased vehicles

For a short-term lease (29 days or less) of an IFTA-qualified motor vehicle, the vehicle's mileage and fuel consumption are reported on the IFTA return of the lessor. For a long-term lease (30 days or more), the lessor and lessee can decide which party is responsible for including the vehicle's mileage and fuel consumption on the IFTA return. The lease agreement must state who is responsible for reporting. A copy of the lease agreement must be kept in the vehicle.


IFTA licensees based in the United States must report fuel quantities and distance traveled in U.S. measurements. Use the conversion table below. Round your totals to the nearest whole gallon or mile.

  • One Liter = 0.2642 Gallons
  • One Gallon = 3.785 Liters
  • One Mile = 1.6093 Kilometers
  • One Kilometer = 0.62134 Miles

Due dates

Most IFTA license holders must file a fuels tax return every calendar quarter.

  • January—March is due April 30
  • April—June is due July 31
  • July—September is due October 31
  • October—December is due January 31

After one year of filing on time, if your IFTA mileage is less than 5,000 miles per year in all IFTA jurisdictions outside of Idaho, you can request to file annually. Send your written request to the Idaho State Tax Commission, Permit Accounting Services, PO Box 36, Boise, Idaho 83722-0410. We'll send your written request to all member jurisdictions where you travel because your request must be approved by all of them.

Annual filers' reporting period
The annual filing period from January to December has a due date of January 31 of the following year.

The Tax Commission will send your IFTA tax return (Form 3150) 30 days before each due date. If you don't receive your return, you can request it through this Web page or by calling us at (208) 334-7806 in the Boise area or toll free at (800) 972-7660, ext. 7806. You're required to file your return by the due date. Information about IFTA jurisdictions, tax rate changes, and other administrative changes by each jurisdiction will accompany your Form 3150.

No activity

You must file your return even if you don't have taxable fuel or travel in Idaho or in any other IFTA jurisdiction. If you have no activity and you're filing electronically, simply select the "File Zero Return" option. If you're preparing a paper return, write "No Activity" across the top of your IFTA return and file it for the appropriate period.

Late reporting, penalties, and interest

The penalty for filing a late return, not filing a return, or underpaying taxes due is $50 or 10% of the total tax due, whichever is greater.

To avoid a late filing penalty, the tax return must be postmarked no later than midnight on the last day of the month following the close of the filing period. If a return is hand-delivered, it's considered received on the date it's delivered to the Tax Commission. If the due date is on a weekend or holiday, the return is due on the next business day. If your return isn't postmarked by the due date, interest is due for each month the return is late (one day late in a month makes the return late for the entire month). Interest is calculated for each jurisdiction that has tax due. Even if you have a net refund, interest still applies to each jurisdiction for any underpayment of fuels use tax to that jurisdiction. Please refer to the Form 3150 instructions for the applicable interest rate.

Amended Idaho IFTA return

If you discover that you've incorrectly reported any information on your IFTA return, you can correct the errors by filing an Amended IFTA Return. To amend your return, use a copy of your original return, Form 3150. Check the "Amended Return" box (or write "Amended" in large letters at the top) and enter the correct figures. Don't just enter the difference between the figures you reported and the correct figures — amended returns must show the figures as they should have been entered on the original return.

If you didn't keep a copy of your original return, contact the Tax Commission for the form. Call (208) 334-7806 in the Boise area or toll free at (800) 972-7660, ext. 7806.

You can amend any previously filed return within the three-year statute of limitations.

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Last updated Aug. 12, 2015