1. Business Use: Section 179 + Bonus Depreciation
Key principle: You can only deduct the business‑use percentage of the vehicle.
If business use = 70%, then only 70% of the cost qualifies for Section 179 or Bonus.
Heavy Vehicle Threshold
A vehicle must have a GVWR of 6,001 lbs or more to qualify for the heavy‑vehicle rules.
2025 Deduction Limits
| Vehicle Type | GVWR | Section 179 (2025) | Bonus Depreciation (Post‑Jan 19) |
|---|---|---|---|
| Heavy SUV | 6,001–14,000 lbs | $31,300 cap | 100% of remaining balance |
| Heavy Truck/Van | 6,001–14,000 lbs | Full cost (up to $2.5M) | 100% |
| Very Heavy (Commercial) | 14,001+ lbs | Full cost (up to $2.5M) | 100% |
Important nuance: SUVs have a capped Section 179 deduction because the IRS classifies them differently from trucks/vans. Trucks/vans can be fully expensed if business‑use % supports it.
Home Office Advantage
If your home office qualifies as your principal place of business, then:
- Trips starting from home → business miles, not commuting
- Much easier to exceed 50% business use, which unlocks:
- Section 179
- Bonus depreciation
- Actual expense method (fuel, repairs, insurance, etc.)
This is one of the most misunderstood advantages in the tax code.
Personal Use: The New 2025 Car Loan Interest Deduction
This is the part that surprises people.
For the first time in decades, personal car loan interest can be deducted — up to $10,000 per year.
Requirements:
- Vehicle must be primarily personal use (>50%)
- New vehicle only
- Assembled in the USA
- Income limits:
- Phases out above $100,000 AGI (Single)
- Phases out above $200,000 AGI (Married Filing Jointly)
Used cars do NOT qualify. Business vehicles do NOT qualify.
This is strictly a personal‑use benefit.
Putting It All Together (The Real‑World Logic)
If the vehicle is mostly business:
You want:
- Section 179 (if eligible)
- Bonus depreciation
- Actual expenses
- Mileage logs
- Home office mileage advantage
If the vehicle is mostly personal:
You want:
- The new $10,000 personal interest deduction
- No Section 179
- No bonus depreciation
- No business mileage
If the vehicle is mixed use:
You must choose which side gives you the bigger tax advantage:
- If business use > 50% → business rules win
- If business use < 50% → personal interest deduction may be more valuable
This is where planning matters.
