Interstate Trucking Companies

This guide provides some basic Idaho income tax information for interstate trucking companies and explains how to calculate your Idaho apportionment factor.

Terms used in this guide

Trucking company – A motor common carrier, a motor contract carrier, or an express carrier paid primarily to transport other’s tangible personal property.

Mobile property – All motor vehicles, including trailers, used directly in moving tangible personal property.

Mobile property mile – The movement of a unit of mobile property a distance of one mile, whether loaded or unloaded. These usually are the same as the miles reported on an International Fuels Tax Agreement (IFTA) tax return.

Original cost – The basis (for federal income tax purposes) of the property when it was bought. Or, if the property has no such basis, the valuation of the property for Interstate Commerce Commission (ICC) purposes. Or, if the cost can’t be determined, the fair market value on the date it was acquired.

Your requirement to file

Idaho law requires a trucking company filing as a corporation or S corporation to file an Idaho income tax return if your company does any of these things during the year:

  • Owns or rents any real or personal property (except mobile property) in Idaho
  • Makes any pickups or deliveries in Idaho
  • Travels more than 25,000 mobile property miles in Idaho
  • Makes more than 12 trips into Idaho

You’ll apportion your income to Idaho.

You’re also required to file an Idaho income tax return if the total mobile property miles traveled in Idaho exceeds 3% of the total mobile property miles traveled by the company in all states.

Read more about apportionment in the “Calculating your apportionment” section below.

Other business entity types

You’re required to file an Idaho income tax return if your total business gross receipts multiplied by the Idaho apportionment factor exceeds $2,500 and you’re either of the following:

  • Nonresident individual operating as a sole proprietorship
  • Limited liability company filing as a disregarded entity on a federal Schedule C

Income subject to apportionment

Start with your federal taxable income from the business and add Idaho’s additions. Subtract both allocable nonbusiness income and Idaho’s subtractions.

This is the income you’ll multiply by your apportionment factor.

Calculating your apportionment

Idaho taxes part of your overall income. The percentage by which it’s taxed is called the apportionment factor. The three-factor apportionment is made up of three numbers, which then are divided by three:

  • Property factor
  • Payroll factor
  • Sales factor (single sales)

The property factor, payroll factor, and sales factor each are calculated to determine the Idaho part of that factor as determined by law. (See Idaho Income Tax Rule 580.01.d.)

Property factor

Owned property is valued at its original cost. Property rented from others is valued at eight times the net annual rental rate.

Include mobile property. The value of mobile property located both inside and out of Idaho during the year is included in “A” in the ratio that those miles in Idaho bear to property miles everywhere.

A divided by B

  • A is the average value of your property owned plus rented property that was used in Idaho during the year.
  • B is the average of all your real and tangible property owned plus rented property that was used everywhere during the year.

Payroll factor

This is compensation paid during the year.

Compensation paid to personnel both inside and out of Idaho during the year is included in “C” in the ratio that their services performed in Idaho bear to their services performed everywhere based on mobile property miles.

C divided by D

  • C is Idaho compensation during the year
  • D is compensation paid everywhere during the year

Sales factor

This is the company’s annual gross receipts.

Idaho receipts for hauling freight, mail, and express are determined at 100% for shipments that begin and end in Idaho. Idaho receipts for hauling these items when the shipment passes through, into, or out of Idaho is determined by the ratio that the mobile property miles traveled in Idaho bears to the total mobile property miles traveled everywhere.

E divided by F

  • E is the company’s Idaho gross receipts
  • F is the company’s gross receipts everywhere

Idaho apportionment example

ABC Inc. is an interstate trucking company based in Utah.

Mobile property miles

During the year it had 29,500 mobile property miles in Idaho and total mobile property miles of 120,000. The percentage of miles traveled in Idaho equals 24.5833% (29,500/120,000).

Property factor

ABC Inc. had a truck and trailer ($60,000) and a warehouse in Utah ($90,000).

TotalIdaho (percentage)
$150,000$14,750 (9.8333%)

Payroll factor

ABC Inc. had Interstate payroll of $20,000 and administrative payroll of $10,000.

TotalIdaho (percentage)
$30,000$4,917 (16.3900%)

Sales factor

ABC Inc. had interstate sales of $500,000.

TotalIdaho (percentage)
$500,000$122,917 (24.5833%)

Final calculations

Percentages added together50.8063%
Divided by…3
Your Idaho apportionment factor16.9354%


Here’s a listing of all our current year business income tax forms. Prior year forms also are available.

Please include a schedule with your Idaho income tax return showing how you determined your company’s Idaho property, payroll, and sales as used in the apportionment factor calculation.


Check our Business Income Tax — Recordkeeping page for guidance on how long to keep your records. Keep all records used to calculate the Idaho apportionment factor, income and deductions.