3 Signs You’re Writing Off Your Company Vehicle Wrong (And How to Fix It)

"Hey Mareaka, I just bought another truck for the crew. My bookkeeper said we can write it off, but how do I know we’re doing it right?

If you’re running a roofing or HVAC business doing $500K or more, chances are you’ve got multiple vehicles on the road.

And if you’re not handling those write-offs the right way, you could be opening yourself up to IRS headaches or missing big tax savings.

Company vehicles are often one of the biggest expenses in your business.

But too many contractors take the wrong approach when it comes to deductions—using Section 179 incorrectly, skipping mileage tracking, or assuming personal use is covered.

One slip-up across a fleet of trucks can add up fast.

What You’ll Learn in This Article

How to avoid IRS red flags on vehicle usage
When NOT to use Section 179 on a truck
Why comparing mileage vs. actual expenses matters
The one policy that protects your deductions

Before we dive into it, let me introduce myself if we haven’t met yet.

I’m Mareaka from Bunch Accounting, and I specialize in helping roofing and HVAC business owners like you make confident, profitable decisions.

Get this wrong, and it’s not just a missed deduction—it’s audit bait.

The IRS specifically targets vehicle write-offs because they’re easy to abuse and hard to verify.

If you’re not documenting usage or choosing the right method, you could lose the deduction entirely (and still owe taxes on top)

Real Money on the Line

One HVAC owner with a fleet of 5 trucks ended up losing over $14,000 in disallowed deductions during an audit—just because they didn’t separate personal from business miles correctly.

Step-by-Step Fix

Here’s how to clean up your vehicle deductions and keep the IRS off your back:

Create a Fleet Usage Policy: Outline when and how vehicles can be used, and require drivers to log mileage.
Use Mileage Tracking Tools: Install apps or devices that track mileage by driver and vehicle.
Double-Check Section 179: Only use it on vehicles used 100% for business—otherwise, it can trigger recapture.
Run the Math: Each year, compare standard mileage vs. actual expense to see which gets you the bigger deduction.
Keep a Log: Monthly summaries should include driver, vehicle, business miles, and personal miles.

When a roofing contractor in Colorado, started tracking each truck with a simple app and added a no-personal-use clause in his crew handbook, he not only secured his write-offs, but also uncovered $6,000 in extra depreciation he could take.

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