What information does the IRS require for each business trip?

The IRS requires four pieces of information for every business trip: the date of the trip, the destination, the business purpose, and the number of miles driven.

Does the IRS accept digital mileage logs?

Yes. The IRS accepts digital records, including those from mileage tracking apps, provided they are 'adequate' and 'contemporaneous'—meaning recorded at or near the time of the trip.

Can W-2 employees deduct mileage in 2026?

Yes. Starting in 2026, W-2 employees can once again deduct unreimbursed mileage as a miscellaneous itemized deduction, subject to a 2% AGI floor. This makes a compliant log essential for employees too.

What is a 'contemporaneous' record?

A contemporaneous record is one created at or near the time of the activity. Reconstructed logs are often rejected by the IRS during an audit.

How long should I keep my mileage records?

You should keep your mileage logs and supporting documentation for at least three to six years, depending on your tax situation.

How to Keep a Mileage Log That Survives an IRS Audit

If you claim a vehicle deduction on your US tax return—whether as a self-employed business owner or a W-2 employee (a deduction that was reinstated for 2026)—you must have documentation to back it up.

In 2026, with the business mileage rate at 72.5 cents per mile, a solid log is worth more than ever. Under Internal Revenue Code Section 274(d), the IRS has the authority to disallow any vehicle deduction that isn't supported by "adequate records."

This guide explains exactly how to build a mileage log that gives you total peace of mind during an audit.

The IRS "Four Pillars" of a Business Trip

For every single business trip you log, the IRS requires four specific details. Missing any of these can disqualify the entry.

Date: When did the trip happen?
Destination: Where did you go? (Specific address or client name).
Business Purpose: Why did you go there? (e.g., "Client meeting," "Job site inspection").
Mileage: How many miles did you drive for that specific business purpose?

Contemporaneous vs. Reconstructed Logs

A contemporaneous record is one made at or near the time of the event. Reconstructing a log from memory months later is a major audit risk. The IRS explicitly states that reconstructed logs carry less weight and are often rejected.

Digital vs. Paper: Which is Better?

The IRS accepts both paper and digital logs. However, digital logs have several advantages:

Timestamps: They prove the record was made contemporaneously.
GPS Data: GPS-verified mileage is much harder for an auditor to dispute.
Organization: Digital logs are easy to search, filter, and export for your accountant.

The Role of Odometer Readings

While you don't necessarily need to record your odometer reading for every stop, you must have two critical readings:

The odometer reading on January 1st.
The odometer reading on December 31st.

These numbers establish the total miles driven for the year. Your business miles are compared to this total to determine your business-use percentage.

What Triggers an IRS Mileage Audit?

Auditors look for patterns that suggest guessing. Common red flags include:

Round Numbers: Logging "10 miles" or "25 miles" for every single trip.
100% Business Use: Claiming zero personal use for a primary vehicle.
Inconsistent Purpose: Using vague terms like "business meeting" without naming the client or location.

How Long to Keep Your Records

Keep your mileage logs and supporting documents (like repair receipts that show odometer readings) for at least six years to be completely safe.

Conclusion

Building an audit-proof mileage log is about consistency. By using a digital tool like automileage.app, you can ensure every trip meets the IRS "adequate records" standard automatically.

Secure your 2026 deduction with automileage.app today.