The S-Corp Vehicle Deduction: Section 179, the 6,000-Pound Rule, and 100% Bonus Depreciation

A general contractor runs his framing crew through an S-corp, and in December he wants to buy an $85,000 heavy-duty pickup and write the whole thing off before the year closes. He heard from another builder that the truck is a full deduction, no depreciation schedule, no waiting. He is right, but only because of a specific weight rating and a stack of rules a sedan would fail. He is theoretical, not an actual EntityIQ client, but the question comes up every fall, and the answer turns on three sections of the code. Get one wrong and the deduction shrinks to a fraction of what he expected.

The corporation has to own it

Depreciation belongs to whoever owns the asset and uses it in a trade or business, so the first question is title. If the S-corp buys the truck and titles it to the corporation, the corporation depreciates it, and any personal driving becomes a taxable fringe benefit on the owner's W-2 under section 61. If the owner buys the truck personally, the corporation cannot depreciate a vehicle it does not own. The clean way to get a personal vehicle onto the return is an accountable plan, where the owner submits mileage or actual costs and the corporation reimburses and deducts them under section 162. That gives you mileage or actual expenses, not a first-year Section 179 write-off, as I cover in the accountable plan guide and IRS Publication 463. For the big deduction the contractor wants, the corporation owns the truck.

The 6,000-pound rule

Section 280F treats a passenger automobile as listed property and caps the depreciation you can claim on it each year. Under section 280F(d)(5), a passenger automobile is a four-wheeled vehicle rated at 6,000 pounds unloaded gross vehicle weight or less, and for a truck or van the test uses the gross vehicle weight rating instead. A vehicle rated above 6,000 pounds falls outside that definition, so the luxury-auto caps do not apply to it. That single line in the code is why a heavy SUV, a full-size pickup, or a cargo van can be written off far faster than a sedan that costs the same. The number is on the door-jamb sticker, and the manufacturer's rating controls, not the curb weight.

The caps this rule lets you skip are real money. For a passenger car placed in service in 2026 and eligible for bonus depreciation, Revenue Procedure 2026-15 limits the first-year deduction to $20,300, then $19,800 in year two, $11,900 in year three, and $7,160 a year after that. An $85,000 sedan still gets deducted, but it dribbles out over most of a decade. Cross the 6,000-pound line and those caps disappear.

Section 179 and the $32,000 SUV cap

Section 179 lets a business expense qualifying property in the year it is placed in service instead of depreciating it over time. For 2026 the overall limit is $2,560,000, phasing out dollar for dollar once you place more than $4,090,000 of property in service, under Revenue Procedure 2025-32. Congress did not want people expensing loaded luxury SUVs against that ceiling, so it carved out a separate limit. For 2026 the Section 179 deduction on an SUV rated between 6,001 and 14,000 pounds is capped at $32,000, up from $31,300 in 2025, under the inflation adjustments in Revenue Procedure 2025-32. The cap only limits the Section 179 portion. A pickup with a cargo bed of at least six feet, or a van that seats more than nine passengers behind the driver, is not treated as an SUV under section 179(b)(5) and can use the full Section 179 limit, which is $2,560,000 for 2026.

One more Section 179 limit matters for an S-corp. Under section 179(b)(3), the deduction cannot exceed the business's taxable income, so it cannot create or deepen a loss, and that limit is tested again at the shareholder level. If the truck would push the S-corp into a loss, Section 179 is suspended and carried forward. Bonus depreciation has no such limit, which is why it usually carries the load on a heavy vehicle.

Bonus depreciation fills the gap

The 2025 tax law, Public Law 119-21, permanently restored 100% bonus depreciation under section 168(k) for qualified property acquired and placed in service after January 19, 2025. Bonus depreciation applies to new and used vehicles as long as they are new to your business, and it is not subject to the $32,000 SUV cap that limits Section 179. On a heavy vehicle, that lets the corporation take Section 179 up to the SUV cap and then deduct the entire remaining basis with bonus depreciation in the same year. On a fully business heavy vehicle you can often run the whole cost through bonus and skip Section 179, which sidesteps the income limit and the SUV cap at once. The deduction lands on Form 4562 and flows to the owner on the K-1.

An S-corp can deduct the full cost of a business vehicle in the first year only if the vehicle is rated over 6,000 pounds gross vehicle weight and the corporation, not the shareholder personally, owns and uses it. For a vehicle over that weight, the corporation combines the Section 179 deduction with 100% bonus depreciation to write off the entire business-use portion in year one, while a lighter passenger car titled to the business is capped at $20,300 for 2026 under Section 280F and comes off over several years instead.

The write-off, in a theoretical case

Back to the contractor and his $85,000 pickup, rated at 8,500 pounds, used 100% for the business and placed in service before December 31, 2026. Because the truck clears 6,000 pounds, section 280F never touches it, and the corporation can expense the entire $85,000 in year one, whether through Section 179 and bonus together or bonus alone. What it saves depends on the owner's marginal bracket, since the write-off reduces the ordinary income on his K-1.

Two honest caveats sit under that number. First, this is acceleration, not free money. The lighter car reaches the same $85,000 of deductions in the end; the heavy vehicle just pulls it into year one, while the owner is in a high bracket. Second, the write-off lowers the ordinary income on the K-1, which is usually also qualified business income under section 199A, so a large deduction can trim the 20% QBI deduction unless the owner is already limited by income or the wage test.

Where it bites back

Section 179 and bonus depreciation are only available if the vehicle is used more than 50% for business, and the deduction is limited to the business-use percentage. If business use later falls to 50% or below, section 280F(b)(2) recaptures the accelerated depreciation, meaning the excess you deducted over straight-line comes back into income in the year use drops. A vehicle that is business one year and mostly personal the next can turn a big first-year deduction into a taxable event, which is why the deduction fits a truck that genuinely runs the business, not a family car parked at the S-corp. Keep a mileage log, because the business-use percentage is a fact you have to prove.

If you run an S-corp and genuinely need a heavy vehicle for the work, the 6,000-pound rule, Section 179, and 100% bonus depreciation together make one of the largest single deductions available to a small business. Buy the vehicle because the business needs it, size the deduction to your real business-use percentage, and run the whole picture, salary and QBI included, in the EntityIQ S-Corp calculator first.

This article is educational and is not legal or tax advice. The figures are 2026 amounts, the contractor is theoretical, and the rules change. Please confirm the current limits and your own facts with a qualified CPA or enrolled agent before you buy.