Every mileage reimbursement rests on a log, and every dispute about mileage is a dispute about whether the log existed before the claim. The log is not the claim; it is the evidence the claim is worked from, and it has to be kept when the driving happens rather than reconstructed when the money is wanted. This page is for the owner setting the rule and the person keeping the record: what a mileage log has to carry, how to track business mileage without it becoming a chore, how to handle a personal car used for work, and why the log matters as much to the business as to the driver. The travel expense report tool on this site turns the log's miles into the claim.
The fields
Date. Starting point and destination, specific enough to check. Business purpose: the customer, the site, the errand. Odometer readings at the start and end, or the trip miles from a mapped route. Running totals for the period. A log with those fields supports both a reimbursement claim and the business's own records; a log missing the purpose supports neither.
How to track business mileage without falling behind
Record each trip the day it happens, in whatever the driver will actually use: a notebook in the car, a phone note, a tracking app, a spreadsheet at the end of each day. The method matters less than the habit. A log written up at month end from memory is a reconstruction, and reconstructions are where reimbursement arguments start.
Personal cars and mixed use
Most small-business driving is in the employee's or the owner's own car. The log records only the business trips; the personal miles are nobody's business but the driver's. Commuting between home and the regular workplace is personal. Travel from the workplace to a customer, between sites, or from home to a temporary work location is business. Write the distinction into the policy so the driver is not deciding it trip by trip.
The mileage log for tax purposes and for the claim are the same log
The business needs the log to support the reimbursement as an accountable-plan payment rather than wages; the self-employed owner needs it to support the deduction. Both need the same fields kept at the same time. Keep one log and use it for both; the travel expense report tool here takes its miles and the rate for the date.
From the log to the claim
At the end of the period, total the business miles per rate period, multiply by the rate for those dates, add tolls and parking with receipts, and submit within the policy's deadline. The log is attached or referenced. PerDiemDesk Pro, at $4 per month for the whole team, keeps the claims against the people who drove and the periods they drove in.
Questions people ask about mileage log
Does a mileage log need odometer readings?
Trip miles from a mapped route are widely accepted; odometer readings are the stronger record. The policy should say which the business requires.
How to track business miles on a personal car?
Log only the business trips with date, destination, purpose and miles. Personal miles are not recorded.
Is a mileage log for tax purposes different from one for reimbursement?
No. Same fields, same timing. Keep one log.