Tax Rules for Selling a Business Truck After 100% Bonus Depreciation and Custom Outfitting

Establishing the Truck's Original Tax Basis

The truck's original tax basis starts with its purchase price, which forms the core of the initial cost. Any amounts spent on custom outfitting—specifically labor for fabrication, materials such as metal and parts, and related custom tools or modifications—are added directly to that purchase price when the work qualifies as a capital improvement that increases the asset's value or useful life.

These customization costs are not treated as separate expenses for basis purposes; instead, they combine with the truck's acquisition cost to create one unified original basis. For example, if a business paid $50,000 for the truck and an additional $20,000 for fabrication labor, metal, and specialized parts, the total original basis equals $70,000 before any depreciation is applied.

Depreciation Treatment Under 100% Bonus Depreciation

The Tax Cuts and Jobs Act of 2017 introduced 100% bonus depreciation for qualifying new and used property placed in service after September 27, 2017, and before January 1, 2023. This rule permitted businesses to deduct the full cost of an eligible truck and its capital improvements in the year the asset was placed in service, rather than spreading the deduction over multiple years.

Qualifying custom outfitting—such as fabrication, metal work, and parts that substantially improve the truck or adapt it to a new use—added to the asset's original basis and received the same treatment. The entire combined cost therefore qualified for the immediate deduction.

Because the full amount was recovered through 100% bonus depreciation, the truck's adjusted basis dropped to zero (or very near zero) at the end of that first year. This outcome holds only for assets acquired and placed in service during the 100% period; later purchases faced phasedown percentages beginning at 80% in 2023.

Distinguishing Capital Improvements from Routine Expenses

The key distinction turns on whether the outlays substantially improve the truck, adapt it to a new or different use, or materially extend its useful life. When custom tools, fabricated metal components, specialized parts, or fabrication labor meet any of those tests, the costs are treated as capital improvements. They are added to the truck’s adjusted basis and recovered through depreciation rather than deducted immediately.

• Capital additions include items that convert a standard pickup into a service vehicle with built-in racks, winches, or storage systems; replace major structural elements with heavier-gauge materials; or install equipment that increases payload capacity or changes the vehicle’s function. These amounts increase basis and are eligible for 100% bonus depreciation when placed in service during the applicable window.
• Ordinary repairs and expenses cover routine maintenance such as oil changes, brake jobs, replacement of worn tires that are not part of an initial upgrade, or minor consumable parts that do not enhance value or extend life beyond normal expectations. These are deducted in full in the year paid.

If the custom outfitting merely restores the truck to its original condition after ordinary wear, the costs remain current expenses. In contrast, any work that adds new functionality or capability moves the outlays into the capital category, even when the same types of materials (metal, parts, labor) are involved.

Calculating Gain or Loss on Sale

When you sell the truck, gain or loss is determined by subtracting its adjusted basis from the selling price: Selling Price − Adjusted Basis = Taxable Gain (or Loss).

After claiming 100% bonus depreciation under the TCJA rules on both the original purchase price and qualifying capital improvements such as custom fabrication, metalwork, and parts, the adjusted basis is reduced to zero (or very close to it). As a result, nearly the entire selling price becomes taxable gain, subject to Section 1245 depreciation recapture taxed as ordinary income up to the total original cost.

Depreciation Recapture and Section 1245 Rules

When a business truck and its custom outfitting qualify for 100% bonus depreciation under the Tax Cuts and Jobs Act rules applicable through 2022, the full original basis—purchase price plus capital improvements such as fabrication, metalwork, and specialized parts—is deducted in the year placed in service. This reduces the adjusted basis to zero. On sale, the IRS applies Section 1245 recapture to treat any gain up to that original combined cost as ordinary income, directly reversing the prior depreciation deductions that had lowered taxable income.

Only amounts realized above the original cost qualify for Section 1231 treatment, which is uncommon for used vehicles. The net effect is deferral of tax, not elimination: the upfront deduction is clawed back as ordinary income when cash changes hands.

Potential Section 1231 Capital Gain Treatment

In the less common scenario where the sale price exceeds the truck's original total cost—purchase price plus all capital improvements such as custom fabrication and parts—the excess amount qualifies as Section 1231 gain. Section 1231 applies to depreciable business property held longer than one year, and net gains receive long-term capital gains treatment rather than ordinary income rates.

For instance, if the combined original basis totaled $70,000 after 100% bonus depreciation and the truck sold for $80,000, the $10,000 above the original basis would be Section 1231 gain taxed at preferential long-term capital gains rates (0%, 15%, or 20% depending on taxable income). The first $70,000 remains subject to Section 1245 depreciation recapture as ordinary income.

Sources

• Tax Cuts and Jobs Act of 2017 on 100% bonus depreciation
• Section 1245 depreciation recapture rules for personal property
• IRS guidance on capital improvements vs ordinary maintenance