What Every Business Owner Needs to Know
For many business owners, self-employed individuals, real estate agents, contractors, consultants, and gig workers, the mileage deduction is one of the largest tax deductions available. Unfortunately, it is also one of the most commonly disallowed deductions during an IRS audit.
The reason? Poor recordkeeping.
The IRS does not require a specific mileage log format, but it does require taxpayers to maintain adequate records that substantiate their business mileage. If you cannot prove your deduction, the IRS may deny it entirely—even if you unquestionably drove the miles.
The IRS Requires Contemporaneous Records
The IRS expects taxpayers to maintain a mileage log that is created at or near the time of each business trip. Waiting until tax season to reconstruct your mileage from memory is generally insufficient and can result in the deduction being disallowed.
A contemporaneous log is considered much more credible than one prepared months later.
What Information Must Be Included?
A proper mileage log should include the following information for every business trip:
- Date of the trip
- Starting location
- Destination
- Business purpose of the trip
- Beginning and ending odometer readings (or total miles driven)
- Total business miles for the trip
At the end of the year, you should also document:
- Beginning-of-year odometer reading
- End-of-year odometer reading
- Total miles driven during the year
- Total business miles
- Personal and commuting miles
These records allow the IRS to determine the percentage of your vehicle’s use for business.
Business Purpose Matters
Simply recording miles driven is not enough.
Your mileage log should explain why the trip was business-related. Examples include:
- Meeting with a client
- Visiting a job site
- Picking up business supplies
- Attending a professional conference
- Traveling between business locations
A vague description such as “business” provides little support during an audit. The more specific your records, the stronger your position.
Can You Use a Mileage Tracking App?
Yes.
The IRS accepts electronic mileage logs and smartphone apps, provided they accurately record the required information. Many apps automatically track:
- Date
- Time
- Mileage
- GPS locations
However, you should still review your trips and add the business purpose before permanently saving the record.
Technology makes compliance easier, but it does not eliminate the requirement to maintain complete records.
Don’t Forget Your Odometer Readings
One of the most overlooked requirements is documenting your total annual mileage.
The IRS often asks for:
- Beginning-of-year odometer reading
- End-of-year odometer reading
Without these figures, it becomes difficult to verify the claimed percentage of business use.
A simple photo of your dashboard on January 1 and December 31 can provide excellent documentation.
Common Mileage Log Mistakes
During IRS examinations, we frequently see taxpayers make the following mistakes:
- Reconstructing mileage months after the fact
- Claiming round numbers (10,000 or 15,000 miles)
- Failing to record the business purpose
- Omitting total annual mileage
- Counting commuting miles as business mileage – It’s personal.
- Keeping inconsistent or incomplete records
These issues can significantly weaken your position during an audit.
How Long Should You Keep Mileage Records?
Generally, taxpayers should retain mileage logs and supporting documentation for at least three years after filing the tax return on which the deduction is claimed. In some situations, longer retention periods may be appropriate, particularly if depreciation is involved or the statute of limitations is extended.
Best Practices
If you use your vehicle for business, consider adopting these habits:
- Record trips daily.
- Photograph your odometer at the beginning and end of each year.
- Save appointment calendars that correspond with your trips.
- Keep receipts for parking and tolls.
- Retain repair and maintenance records.
- Use a reputable mileage-tracking app as a backup—not a substitute for documenting the business purpose.
Final Thoughts
The mileage deduction can save business owners thousands of dollars each year, but only if it is properly documented.
Remember, the IRS is not simply looking for the number of miles you drove. It wants evidence showing when you traveled, where you went, why you went, and how many miles were driven.
Maintaining a complete mileage log throughout the year takes only a few minutes each week, yet it can protect one of your most valuable tax deductions if the IRS ever comes calling.
If you have questions about vehicle deductions, IRS recordkeeping requirements, or are facing an IRS audit, contact our office. We help individuals and businesses maximize legitimate deductions while ensuring they have the documentation needed to withstand IRS scrutiny.
