How to Reconstruct a Mileage Log (When You Forgot to Track)

If you did not track mileage during the year, you can still reconstruct a log. But reconstructed logs are weaker than contemporaneous ones, and the IRS knows it. Here is how to do it as defensibly as possible.

What the IRS thinks of reconstructed logs

The Tax Court has ruled against drivers in dozens of cases where the only mileage record was a year-end reconstruction, even when the underlying business activity was real. The IRS will accept a reasonable reconstruction in some cases. Typically when supporting evidence is strong and the claim is not implausible. But reconstruction is the deduction risk path of last resort, not a strategy.

Step 1: Pull all the data sources you have

• Calendar entries for client meetings, job sites, deliveries. These timestamp where you were and why.
• Email correspondence with destinations and dates ("Confirming our 2pm meeting at Smith Co.").
• Gas receipts with dates and stations. These prove driving days and approximate routes.
• Toll receipts and EZ-Pass statements. Exact route timestamps.
• Platform data for gig drivers: Uber, DoorDash, Lyft, Instacart all provide trip-level data on request.
• Bank and credit card statements for purchases at distant locations.
• Phone location history from Google Maps Timeline or iOS Significant Locations (the most thorough but requires careful manual review).
• Service appointment records for vehicle inspections, oil changes. These show odometer readings on specific dates.

Step 2: Build a trip table

For each business trip you can substantiate, fill in the four IRS-required fields: date, destination, business purpose, miles. Use the available evidence to anchor each row. Be honest. If you cannot substantiate a trip, leave it out of the reconstruction. An over-reconstructed log is worse than a smaller, defensible one.

Step 3: Capture odometer evidence

Pull odometer readings from any service-record receipts (oil change, tire rotation, inspection). The IRS uses total annual miles to gut-check your claimed business miles. If your reconstruction claims 25,000 business miles on a vehicle that only put on 24,000 total per service records, you have a problem.

Step 4: Add a methodology note

Document HOW you reconstructed the log: "Trips reconstructed from calendar appointments, gas receipts, and Uber driver-history export." A clear methodology note signals to the IRS that you are being honest about the reconstruction rather than fabricating numbers.

What NOT to do

• Do not round to suspicious numbers (exactly 20,000 business miles is a red flag).
• Do not reconstruct trips you cannot actually substantiate. "I probably drove there" is not a deductible mile.
• Do not claim 100% business use on a single personal vehicle. Even high-mileage rideshare drivers have some personal driving.
• Do not reconstruct multiple consecutive years from memory. The IRS will assume the entire pattern is fabricated.

What to do for next year

Start using a tracker NOW. Auto-detection apps timestamp trips at the moment they happen, which makes the resulting log contemporaneous by construction. The IRS treats contemporaneous logs differently than reconstructed ones; the audit-defense difference is enormous.

Stop reconstructing. Auto-track every business mile. Start free with TruMile →