Accelerated depreciation may let you write off your new truck faster, even with an auto loan. Learn what is deductible this year and how to qualify. Start now with Curler Accounting.

Short Answer: You Cannot Deduct the Loan Principal, But You Can Deduct Depreciation and Some Interest

If you bought a new truck for your business, you cannot write off the principal portion of the auto loan. The IRS treats the truck as a business asset. You recover the cost through depreciation over time or faster using accelerated depreciation methods like Section 179 and bonus depreciation. You can also deduct the business portion of the loan interest and ongoing operating costs such as fuel, insurance, and maintenance. The size and timing of your deduction depend on business use, vehicle weight, your taxable income, and which method you choose.

What Does it Mean to Write Off a Truck?

Writing off a vehicle is not a single line item. It is a mix of deductions you can take if the truck is used for business. For most owners the three largest pieces are depreciation, interest, and operating expenses. These are limited to your business use percentage. If you use the truck 80 percent for business, you can usually deduct 80 percent of the allowed costs.

Principal vs Interest on the Auto Loan

Loan principal is not deductible as an expense. It is part of the truck’s cost basis, which you recover through depreciation. The interest on a business vehicle loan is deductible to the extent of business use. If your annual interest is 3,000 dollars and business use is 80 percent, you could deduct 2,400 dollars of interest.

Depreciation Basics

Depreciation spreads the cost of your truck over its useful life. Under the default MACRS system for vehicles, you claim a portion each year. With accelerated depreciation, you can write off much more in the first year using Section 179, bonus depreciation, or both, if you qualify.

Your Main Choices: Standard Mileage or Actual Expenses

You generally choose one method in the first year you place the truck in service for business.

• Standard mileage rate, you deduct a per mile amount set by the IRS for business miles. This method includes a built-in depreciation factor and usually cannot be combined with Section 179 or bonus depreciation.
• Actual expense method, you track and deduct a business share of fuel, insurance, registration, repairs, tires, interest, and depreciation. This is the method you must use if you want accelerated depreciation on a purchased truck.

Many small business owners choose actual expenses for pickups and work trucks because it often creates a larger first year deduction, especially when accelerated depreciation applies.

Accelerated Depreciation Explained

Accelerated depreciation lets you take more of the truck’s cost sooner. This is valuable when cash flow or current year tax savings matter. The two main tools are Section 179 and bonus depreciation.

Section 179 Deduction

Section 179 allows you to expense part or all of the truck’s business cost in the year placed in service. To qualify, business use must exceed 50 percent. The deduction is limited by your taxable business income, and there are annual dollar caps that change each year. Certain SUVs have a special cap. Heavy pickups and cargo vans designed for business may qualify for larger Section 179 deductions than passenger vehicles. If your income is low, Section 179 may be limited, but you can still use bonus depreciation or regular MACRS on the remaining basis.

Bonus Depreciation

Bonus depreciation is another form of accelerated depreciation. It applies after Section 179 and can create a large first year deduction. Bonus depreciation has been phasing down in recent years under current law. The exact rate depends on the tax year you place the truck in service. Bonus depreciation can apply to new or used trucks as long as you did not previously use the vehicle and other IRS conditions are met. Some states do not follow the federal bonus rules, so a state return might spread the deduction over more years. Curler Accounting will model the federal and Wisconsin impact so you are not surprised at filing time.

Regular MACRS Depreciation

If you do not or cannot use accelerated depreciation, you can still depreciate the business cost of the truck over several years using MACRS. The annual deduction is smaller but steady. This approach can be smart if you expect to be in a higher tax bracket later or want to avoid triggering the mid quarter convention by placing too much property in service at the end of the year.

Do You Qualify for a Big First Year Write Off?

Eligibility is mostly about business use and the type of vehicle.

• Business use over 50 percent, needed for Section 179 and bonus depreciation. Document with a mileage log that shows business, commuting, and personal miles.
• Placed in service this year, you must start using the truck for business this year, not just purchase it.
• Type of vehicle, pickups and SUVs over 6,000 pounds gross vehicle weight rating often qualify for larger deductions than lighter passenger vehicles. Certain passenger autos are subject to annual luxury auto caps.
• Taxable income, Section 179 is limited to business income, but bonus depreciation does not have the same income limit.
• Ownership, you must own the vehicle or have a qualifying capital lease. If your S corporation owns the truck, title and payments should match the entity, or use a proper accountable plan to reimburse you.

What if the Truck is Financed?

Financing does not block your deduction. For tax purposes, you treat the purchase price, sales tax, title fees, and improvements as basis. You can still use accelerated depreciation on the business portion of that basis as long as you meet the rules. You deduct interest separately. The loan principal has no direct deduction because depreciation already recovers that cost. This is why a financed truck can still create a large first year write off even if you only made a small down payment.

Real World Examples

Example 1: Contractor Buys a Heavy Pickup

Assume you buy a 70,000 dollar pickup used 80 percent for business as a self employed contractor. You put it in service in June and finance the truck. You track all miles and expenses. With actual expenses, you can consider Section 179 to expense a large part of the 56,000 dollar business basis, subject to income and vehicle rules. If you still have remaining basis, you may claim bonus depreciation if you qualify, then regular MACRS on what is left. You can also deduct 80 percent of the loan interest plus 80 percent of insurance, fuel, and maintenance. A strong current year profit and good records could support a very large first year deduction.

Example 2: Consultant Buys a Lighter SUV

You buy a 45,000 dollar SUV used 60 percent for business. Because the SUV is under certain weight thresholds, annual luxury auto limits may cap the depreciation you can claim each year. You still get a deduction, but it may be spread out and smaller in year one. If you used the standard mileage method, you could not also take Section 179 or bonus depreciation, so you would compare outcomes before you file. Curler Accounting runs both methods to see which produces the best long term result.

Example 3: S Corporation Owner Driver

Your S corporation pays you a salary and you bought a truck in your name. The corporation cannot deduct your personal truck costs unless it adopts an accountable plan and reimburses you based on actual expenses or the standard mileage method. If the corporation owns the truck, it can claim depreciation. Get title, insurance, and loan documents aligned with the ownership structure to make recordkeeping clean and defensible.

Common Limits and Pitfalls

• Commuting is not business, trips from home to a regular workplace are personal. A home office may change where your trip starts.
• Business use below 50 percent, you cannot use Section 179 or bonus depreciation. You must use regular MACRS and may have to recapture accelerated deductions if business use later drops.
• Mixed use without logs, the IRS expects contemporaneous mileage logs. Recreated logs after the fact are risky.
• Standard mileage chosen in year one, you generally cannot switch later to accelerated depreciation for that vehicle.
• End of year purchases, buying too much property in the last quarter can trigger the mid quarter convention, which reduces first year MACRS. Plan timing with your CPA.
• State differences, some states do not follow federal bonus depreciation or Section 179 limits. Wisconsin treatment can differ. Curler Accounting adjusts your plan for both returns.
• Sales tax and fees, usually added to basis for depreciation, not deducted as a separate expense in the year of purchase.
• Leases, true operating leases are expensed monthly, but capital leases and lease incentives can be treated more like purchases. The rules here are technical.

Electric and Clean Vehicle Considerations

If your new truck is electric, you may be eligible for a clean vehicle credit for personal purchases or a commercial clean vehicle credit for business. Credits reduce your tax dollar for dollar and can interact with depreciation by reducing basis before you calculate deductions. Eligibility depends on weight, use, where the vehicle is made, and other requirements. Because credits and depreciation interact, model the total picture before filing. Curler Accounting can guide you through the credit and accelerated depreciation math.

What Records You Need to Keep

• Mileage log, start and end odometer readings for each business trip, purpose, and location.
• Purchase documents, bill of sale, financing agreement, sales tax, and title paperwork.
• Operating costs, fuel, insurance, repairs, maintenance, registration, and any accessories used for business.
• Proof of business use, calendars, client appointments, job site records, and invoices.
• Entity documentation, if your business owns the truck, keep the title, policy, and payments in the entity name or use a clear accountable plan.

How to Decide Between Section 179, Bonus, and MACRS

Your decision is about timing, cash flow, and risk. Here is a simple framework we use at Curler Accounting.

1. If business use is over 50 percent and profits are strong, consider Section 179 to match deductions to cash needs. Remember the income limit and SUV caps.
2. Use bonus depreciation to accelerate any remaining basis if you qualify and want more in year one. Keep an eye on the current bonus rate and state conformity.
3. Stick with MACRS when you expect higher future income, want to avoid mid quarter issues, or cannot meet the 50 percent business use test.
4. Run both standard mileage and actual expense models before making a final choice in the first year.
5. Do multi year tax planning so you do not run out of deductions later when income is highest.

FAQs

Can I write off the entire cost of my new truck this year?

Maybe. If you qualify for accelerated depreciation and Section 179, and your truck meets the weight and use tests, you might write off most or even all of the business cost in year one. Your income, state rules, and business use percentage matter. Financing does not prevent the deduction.

Is loan principal deductible?

No. Principal is recovered through depreciation. Only the business portion of loan interest is deductible as an expense.

Does the truck have to be new?

No. Section 179 and bonus depreciation can apply to new or used trucks as long as the vehicle is new to you and other conditions are met.

What if I am an employee who uses my own truck for work?

Employees generally cannot deduct unreimbursed vehicle expenses on their federal return right now. Ask your employer about an accountable plan for reimbursements. If you are self employed, you can deduct eligible business use.

Can I switch from standard mileage to actual expenses later?

If you started with standard mileage in the first year, you usually cannot switch to accelerated depreciation for that vehicle later. Choose carefully in year one and get advice before you file.

How does a refinance affect my deductions?

Refinancing changes your interest deduction going forward, not your basis. Your depreciation schedule continues on the remaining basis. Keep the new loan documents with your tax records.

What about rolling negative equity into the new loan?

Negative equity rolled into a new loan is not part of the truck’s depreciable basis. Only the cost of the new truck and related purchase costs count for depreciation. The interest portion tied to the rolled amount can be tricky. Get tailored advice before you file.

Why Work With Curler Accounting on Vehicle Write Offs

Curler Accounting & Tax Services, LLC brings practical, local expertise to every deduction decision. Owner Matt Curler, CPA, has more than 20 years in tax, finance, and treasury management with experience at KPMG and Harley Davidson. He served 18 years in the Wisconsin Army National Guard as a Military Police Officer, including two Iraq deployments, and then six years with the Milwaukee Police Department. That background shows up in how we work, disciplined, accurate, and committed to your success.

Services Tailored to Your Truck and Your Books

• Tax Preparation and Planning, minimize liabilities with smart timing and accelerated depreciation strategies.
• Bookkeeping, accurate tracking of vehicle costs and basis.
• Payroll Solutions, clean reimbursements with accountable plans.
• Cash Flow Optimization, turn tax savings into working capital.
• Business Tax and Compliance, clear guidance for LLCs, S corporations, and partnerships.
• IRS Representation, support if a vehicle deduction is questioned.
• Entity Formation, choose structures that make vehicle ownership and reimbursement simple.

What Clients Appreciate About Curler Accounting

• Personalized Service, hands on help that fits your business.
• Military Precision and Integrity, ethical, disciplined financial management.
• Small Business Focus, practical strategies for growth.
• Community Commitment, active in Rotary Club and VA Hospital volunteer work.
• Local and Virtual Services, serving Mequon and clients statewide online.

Next Steps: Get a Clear Number Before You Buy or File

Accelerated depreciation can make a big difference, but the best outcome depends on your facts. Before you sign the purchase order or choose a method on your return, talk with Curler Accounting. We will estimate your first year write off, compare Section 179, bonus depreciation, and MACRS, and map out the cash flow. We will also check Wisconsin treatment so your state return is aligned with the plan. Bring your mileage estimates, truck specs, price quote, down payment, and expected income. We will do the rest.

Ready to see how much of your new truck you can write off this year, even with an auto loan? Contact Curler Accounting & Tax Services, LLC today. Matt Curler and our team will help you document business use, choose the right method, and file with confidence.

This blog is for general education. Tax rules change and your situation is unique. Always consult a CPA. Curler Accounting is here to help you make the most of accelerated depreciation and every other deduction you qualify for.