Understanding Automobile Expense Deductions and Substantiation: Mileage Method vs. Actual Expense Method

When it comes to deducting automobile expenses on your taxes, there are two primary methods to consider: the mileage method and the actual expense method.  Each has its own set of rules, benefits, and potential drawbacks.  Choosing the right method depends on your specific situation and how you use your vehicle for business purposes.

The Mileage Method

The mileage method, also known as the standard mileage rate, allows you to deduct a fixed amount per mile driven for business purposes.  This rate is set annually by the IRS and is designed to cover the general costs of operating a vehicle, including fuel, maintenance, insurance, and depreciation.

For the tax year 2024, the standard mileage rate is 67 cents per mile (note that this rate can change annually, so always check the latest IRS guidelines).

Advantages of the Mileage Method:

1. Simplicity: The mileage method is straightforward.  You simply track the number of business miles driven during the year and multiply that by the IRS standard mileage rate.
2. Record-Keeping: You only need to keep track of your mileage, making it easier to maintain records.
3. Predictability: The deduction amount is predictable, making it easier to estimate your tax savings.

Disadvantages of the Mileage Method:

1. May Result in a Lower Deduction: Depending on your vehicle’s actual operating costs (gas, oil changes, maintenance & repairs, etc.), the mileage method may result in a lower deduction compared to the actual expense method.
2. Restrictions: If you use five or more vehicles for business purposes simultaneously (such as in a fleet), the mileage method is not allowed. 

The Actual Expense Method

The actual expense method allows you to deduct the actual costs associated with operating your vehicle for business purposes.  This includes expenses like gas, oil, repairs, tires, insurance, registration fees, licenses, and depreciation.  To use this method, you need to keep detailed records of all expenses and determine what percentage of the vehicle’s use was for business.

Advantages of the Actual Expense Method:

1. Potential for Higher Deductions: If your vehicle is expensive to operate or you drive it extensively for business, the actual expense method may yield a larger deduction.
2. Flexibility: You can deduct a wider range of expenses, which can be beneficial if your vehicle incurs significant costs.

Disadvantages of the Actual Expense Method:

1. Complex Record-Keeping: This method requires detailed record-keeping of all vehicle-related expenses.  You also need to determine the percentage of time the vehicle is used for business, which can add complexity.
2. Time-Consuming: Tracking every expense and calculating depreciation can be more time-consuming than simply recording your mileage.

Depreciation 

Depreciation is a significant factor in the actual expense method, allowing you to deduct the wear and tear on your vehicle over time.  However, the IRS imposes limits on how much you can depreciate each year.  Additionally, businesses may benefit from the IRC Section 179 deduction, which allows for an immediate expense deduction on the purchase of certain qualifying assets, including vehicles, rather than depreciating them over several years.  Bonus depreciation may provide further first year depreciation benefits on qualified vehicles. 

Depreciation Caps for 2024

For passenger vehicles placed in service in 2024, the IRS sets limits on how much depreciation can be deducted each year:

1. First Year: $12,400 (increased to $20,400 if bonus depreciation is allowed)
2. Second Year: $19,800
3. Third Year: $11,900
4. Each Succeeding Year: $7,160 until the vehicle is fully depreciated

These limits cap the annual depreciation deduction regardless of the vehicle’s actual cost or depreciation rate.

IRC Section 179 Deductions for 2024

IRC Section 179 allows businesses to deduct the full purchase price of qualifying equipment, including vehicles, in the year they are placed in service.  However, specific caps apply to certain vehicles:

1. Passenger Vehicles: Section 179 deductions are capped at the passenger vehicle limits above, limiting the combined Section 179 and depreciation deduction to the annual limits.
2. Luxury Vehicles: Vehicles with a gross vehicle weight rating (GVWR) of less than 6,000 pounds are subject to the same caps.
3. Heavy Vehicles (SUVs, Trucks, and Vans): Vehicles with a GVWR of more than 6,000 pounds but less than 14,000 pounds are eligible for a higher Section 179 deduction.  For these vehicles, the maximum deduction is $30,500 in 2024.  This can often allow you to expense the full cost of the vehicle in the year of purchase if it qualifies.

Key Points:

• Business Use: To qualify for Section 179 and depreciation deductions, the vehicle must be used more than 50% of the time for business purposes.  If business use drops to less than 50%, depreciation recapture may be required.
• Combination of Deductions: After applying the Section 179 deduction, any remaining vehicle cost can still be depreciated, which is particularly useful for high-cost heavy vehicles. 

Substantiation and Record-Keeping

Regardless of whether the actual or mileage method are used, adequate substantiation is required.  Automobiles are considered listed property, and no deductions for listed property are allowed on the basis of approximations or unsupported testimony.  The elements of expenditure or use with respect to an automobile that the taxpayer’s records or statement with supporting evidence must substantiate are:

An adequate record of use generally must be written.  However, a record of the business use of listed property prepared in a computer memory device with the aid of a logging program will constitute an adequate record.  For example, a cell phone application (app) that tracks business mileage may suffice.

The level of detail required to substantiate business expenditure or use can vary depending on the facts and circumstances.  For example, a taxpayer who uses a truck for both business and personal purposes and whose only business use of the truck is to make deliveries to customers on an established route may satisfy the adequate record requirement by recording the length of the delivery route once, the total number of miles driven during the tax year, and the date of each trip at or near the times of the trips.

Sampling Based on Records Maintained for Portion of Tax Year

A taxpayer may maintain an adequate record for portions of a tax year and use that record to substantiate the amount of business use for the entire tax year, provided that the taxpayer can demonstrate by other evidence that the periods for which an adequate record is maintained are representative of the use throughout the tax year. 

The taxpayer must show that the periods chosen are truly representative of the business activities for the entire year.  For example, the following factors would refute the appropriateness of the sampling technique:

• The taxpayer’s business activity is erratic or changes substantially between the sampling periods and the remainder of the tax year.
• The taxpayer obtains a second car during the year or gives up a second (or third, etc.) car during the year.

This sampling method is also not permitted to substantiate the business or investment use of an employer’s vehicle that is made available for use by more than one employee during the year.

Conclusion

Along with these other small business tax deductions to know about, deducting automobile expenses can significantly reduce your tax liability, but it’s essential to choose the method that best fits your situation.  Whether you opt for the simplicity of the mileage method or the potential for greater deductions with the actual expense method, understanding the rules and limitations—especially regarding depreciation—will help you make an informed decision.

As always, it’s advisable to consult with a tax professional to ensure you’re taking full advantage of the deductions available to you while complying with IRS regulations.  If you have any questions about automobile expense deductions and how it can benefit your tax situation, please reach out to a member of our team.

Aura Advisors is a boutique tax consulting and compliance firm working with start-ups, emerging growth companies, and affluent individuals. Making it safer for good people and good companies to continue to do good things.