Idaho State Tax Commission

Idaho State Tax Commission

IFTA Licensees


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):

Preparing Idaho's IFTA return (Form 3150)

Follow the five steps below to ensure that you're filing your IFTA return correctly. Keep good records (see Recordkeeping), and your Idaho IFTA return will be much easier to file.

Tip: See these steps on a sample IFTA return.

Step 1: Average fleet miles per gallon

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 (nontaxable) miles, miles traveled under a temporary fuels tax permit, and nonrevenue (deadhead, bobtail, etc.) 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 was used to run power-take-off (PTO) or auxiliary engines; you must include all of the fuel in this calculation.

Step 2: Total distance traveled

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 (nontaxable), temporary permit). If the total miles and taxable miles will be different, be sure to claim your off-highway (nontaxable) miles. Check with each jurisdiction you intend to claim nontaxable miles for its definition.

Beginning January 1, 2017, you must use Form 75, Idaho Fuel Use Report, and accompanying worksheets to make all claims for Idaho nontaxable miles by an IFTA fleet.

Step 3: Report taxable distances

Report taxable miles for each fuel type. Most jurisdictions don't have distance exemptions reported on the IFTA return (including Idaho), so your total miles will equal your taxable miles in most cases.

If you operate in multiple jurisdictions, contact each jurisdiction or check the IFTA website to determine which jurisdictions have distance exemptions and to get a definition of their nontaxable distance. 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

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

Total the tax-paid gallons for each jurisdiction. This is the 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.

Visit the IFTA website for more information on "Tax-paid fuel purchases" and "Fuel purchased untaxed."


Some jurisdictions charge a fee ("surcharge") in addition to the fuel use tax. The surcharge jurisdictions and their surcharge rates are listed on the IFTA fuel taxes rate chart that's mailed to you with your IFTA return (Form 3150). You can also find the information on the IFTA website.

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:

  1. Enter the surcharge rate in the Tax Rate column.
  2. Enter the same total distance, taxable distance, and taxable gallons you entered on the previous line.
  3. 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.
  4. Net Taxable Gallons will be the same as the figure for Taxable Gallons.
  5. 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, report the vehicle's distance and fuel consumption on the lessor's IFTA return.
  • For a long-term lease (30 days or more), the lessor and lessee must decide which party is responsible for including the vehicle's distance and fuel consumption on the IFTA return.

Your lease agreement must state who is responsible for reporting. You must keep a copy of the lease agreement in the leased vehicle.


IFTA licensees based in the U.S. 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 distance.

  • One liter = 0.2642 gallons
  • One gallon = 3.785 liters
  • One mile = 1.6093 kilometers
  • One kilometer = 0.62134 miles

These are equivalents for a gallon if you're using gaseous fuels:

  • Gasoline = 126.67 cubic feet or 5.66 pounds of compressed natural gas (ref.: R222)
  • Diesel = 6.06 pounds of liquefied natural gas (ref.: P1320)

These are equivalents for a liter if you're using gaseous fuels:

  • Gasoline = 1.0 cubic meters or 0.678 kilograms of compressed natural gas (ref.: R237)
  • Diesel = 0.73 kilograms of liquefied natural gas (ref.: P1320)

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

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 by contacting the IFTA Help Desk. You must file your return by the due date to avoid penalties and sanctions. We'll include information about IFTA jurisdictions, tax rate changes, and other administrative changes with your Form 3150.

File online: Use TAP, Idaho's free online portal, up to 30 days before the due date.

Requesting annual filing frequency

You can request to file annually if you file on time for a year and your IFTA distance is less than 5,000 miles per year in all IFTA jurisdictions outside Idaho. Send your written request to the Idaho State Tax Commission, Permit Accounting Services, PO Box 36, Boise ID 83722-0410.

Reporting period for annual filers

You'll report the period Jan. 1 through Dec. 31 by January 31 of the following year.

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.

  • Filing electronically? Simply submit the return without any numbers.
  • Filing 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

You are charged a penalty of $50 (or 10% of the total tax due, whichever is greater), if you:

  • File a late return,
  • Don't file a return, or
  • Underpay your taxes.

To avoid a late filing penalty, the tax return must be postmarked or e-filed by 11:59 p.m. on the last day of the month following the close of the filing period. If you hand-delivered it, 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.


Late returns are charged interest for each month (or portion of a month – even a day) the return is late. 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. See the Form 3150 instructions for the interest rates that apply.

Amended Idaho IFTA return

If you find that you've incorrectly reported information on your Idaho IFTA return, you can correct the errors by filing an amended Idaho IFTA Return. To amend your return, make 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 IFTA Help Desk.

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

August 28, 2017

This information is for general guidance only. Tax laws are complex and change regularly. We can't cover every circumstance in our guides. This guidance may not apply to your situation. Please contact us with any questions. We work to provide current and accurate information. But some information could have technical inaccuracies or typographical errors. If there's a conflict between current tax law and this information, current tax law will govern.