How to keep a mileage log you can actually stand behind

The mileage log is the record most small businesses do not keep, and the one preparers ask about first.

What each trip needs

Four things: the date, where you went, why (which job or client), and the miles. Odometer readings at the start and end of the year help. A log with those four things, kept as you go, is what the people who review these records expect to see.

Keep it from the truck

Nobody writes the trip down at home that night. Keep it on your phone. York takes "38 miles round trip to the Auburn job" over your home Wi-Fi and files the date, the job and the miles; by month end it can tell you the total without anyone adding up slips.

If you have not been keeping one

Reconstruct from what exists: your calendar, your invoices (each job is a trip), and maps for the distances. Mark it as reconstructed. It is weaker than a contemporaneous log but far better than a round number. Then start the habit for the rest of the year.

What this is not

This is how to keep the record, not how it is treated on a return. Rates, methods and what counts as business travel are questions for your tax preparer.