What is the useful life for depreciation of a semi-truck

For federal income tax purposes, a semi-truck (specifically the tractor unit) has a useful life of 3 years under the General Depreciation System (GDS).

If you are depreciating the trailer attached to the truck, it falls into a separate asset class with a 5-year useful life.

1. Introduction

The depreciation of a semi-truck is governed by the Modified Accelerated Cost Recovery System (MACRS). The IRS separates the "power unit" (the tractor) from the "trailer" into distinct asset classes, each with its own recovery period.

• Who this applies to: Owner-operators, trucking companies, and businesses owning heavy transport vehicles.
• What it is: The statutory time period over which you deduct the cost of the vehicle.
• Why it matters: Misclassifying a tractor unit (3-year property) as a general heavy truck (5-year property) delays your tax deductions. Conversely, applying a 3-year life to a trailer or a rigid heavy truck (like a dump truck) creates an audit risk for underpayment of tax in early years.

2. Core Explanation

Tractor Units (The "Semi")

Under Publication 946, "Tractor Units for Use Over-the-Road" fall under Asset Class 00.26.

• GDS Recovery Period: 3 Years
• ADS Recovery Period: 4 Years (Required for certain electing farming businesses or if used predominantly outside the U.S.)
• Depreciation Method: The default method is 200% Double Declining Balance (switching to straight-line when advantageous), using the Half-Year Convention (unless more than 40% of assets were placed in service in Q4, which triggers the Mid-Quarter Convention).

Key Definition: This class applies specifically to the "tractor unit"-the motor vehicle designed to tow a trailer. It does not include the trailer itself or heavy trucks where the cargo box is permanently attached to the chassis (like a box truck or dump truck).

Trailers

Trailers and trailer-mounted containers fall under Asset Class 00.27.

• GDS Recovery Period: 5 Years
• ADS Recovery Period: 6 Years

Bonus Depreciation (2026 Tax Year)

Under the Tax Cuts and Jobs Act (TCJA) phase-out schedule, "Bonus Depreciation" (Section 168(k)) allows you to deduct a percentage of the cost immediately in the first year.

• 2024: 60%
• 2025: 40%
• 2026: 20%
• 2027: 0%

Note: While the "One Big Beautiful Bill Act" (OBBB) introduced in 2025 terminated several green energy credits, it generally preserved the existing phase-down schedule for standard business property depreciation.

Section 179 Expense

You may elect to expense 100% of the cost of the semi-truck under Section 179, provided you have sufficient taxable business income to offset the deduction.

• 2026 Limits: The deduction limit is indexed for inflation (estimated >1.25 million), with a phase-out threshold beginning around 3.1 million in total equipment purchases.
• Heavy Vehicle Exception: Because a semi-truck has a Gross Vehicle Weight Rating (GVWR) far exceeding 6,000 lbs, it is not subject to the $30,500 limit that applies to smaller SUVs and crossovers.

Audit and Practitioner Considerations

The depreciation of heavy vehicles is a frequent target for IRS adjustments due to classification errors.

1. Tractor vs. Heavy Truck Distinction (Class 00.26 vs. 00.242)

   • Challenge: The IRS often challenges the classification of "straight trucks" (e.g., dump trucks, cement mixers, large delivery vans) as 3-year property.
   • Rule: Only "Tractor Units" (articulated vehicles designed to pull trailers) are 3-year property. "Heavy General Purpose Trucks" (actual unloaded weight ≥ 13,000 lbs) are 5-year property (Asset Class 00.242).
   • Risk: If you depreciate a dump truck over 3 years, the IRS will reclassify it to 5 years and assess interest on the timing difference.

2. Repairs vs. Improvements (The "Overhaul" Trap)

   • Challenge: Expensing a major engine rebuild or "in-frame" overhaul as a repair.
   • Rule: Under the Tangible Property Regulations (TPR), costs that restore the unit to a "like-new" condition, extend its class life, or adapt it to a new use must be capitalized and depreciated.
   • Documentation: Maintain records showing the work was maintenance to keep the truck in operating condition, rather than a betterment that increased its value or longevity substantially beyond its original state.

3. Personal Use & Commuting

   • Challenge: While rare for semi-trucks, any personal use (e.g., using the bobtail for personal errands) technically requires an allocation of business use percentage.
   • Documentation: Mileage logs are less critical for qualified non-personal use vehicles (defined in Reg. § 1.274-5(k)), which includes semi-trucks, but the vehicle must be clearly marked and designed such that personal use is de minimis.

4. Heavy Highway Vehicle Use Tax (HVUT)

   • Compliance: Ensure Form 2290 is filed for any vehicle with a gross weight of 55,000 lbs or more. The IRS may cross-reference your depreciation schedule with your Form 2290 filings to ensure all assets are accounted for.

3. Summary

• Tractor Unit (Semi): 3-Year GDS Life (Asset Class 00.26).
• Trailer: 5-Year GDS Life (Asset Class 00.27).
• Straight Truck (Dump/Box): 5-Year GDS Life (Asset Class 00.242).
• 2026 Depreciation Options:
  • Standard MACRS: 200% Declining Balance over 3 years.
  • Bonus Depreciation: 20% of cost.
  • Section 179: 100% immediate write-off (subject to income limitations).

4. Suggested Next Steps

• Review Invoices: Ensure the purchase invoice clearly separates the cost of the tractor unit from the trailer if they were purchased as a package.
• Check Placed-in-Service Date: Confirm the exact date the truck was ready and available for use to determine if the Mid-Quarter Convention applies (if >40% of assets were bought in Q4).
• File Form 2290: Ensure the Heavy Highway Vehicle Use Tax return is filed by August 31st (or the end of the month following the month of first use).
• Draft Depreciation Schedule: Prepare Form 4562 selecting "3-year property" for the tractor.