Mileage log for tax: what the tax office actually needs

A mileage log (Fahrtenbuch) is only as good as what it records. A spreadsheet that just says 'customer visit — 20 km' will be rejected. The tax office wants specific, verifiable entries.

What a valid entry must contain

For every business trip you need: the date, the start location, the end location, the purpose, and the kilometres driven. Some authorities also want the odometer reading at start and end. Private trips must be marked as private — a log with only business trips is a red flag.

The rules differ by country

Germany, Austria and Switzerland (GoBD) have strict rules and want a proper PDF log. The UK (HMRC), US (IRS) and Canada (CRA) accept digital logs too, but the required detail — and the allowed mileage rate — differs. Logging more detail than required never hurts; logging less gets you audited.

Why a digital log beats a paper notebook

A paper log is easy to lose and easy to 'backfill' — which auditors know. A digital log with GPS-calculated distance and timestamps is harder to dispute, because the numbers are computed, not estimated.

Keep it month by month

Don't wait until December to reconstruct the year. A monthly summary of business vs private kilometres — with the allowance already calculated — keeps you audit-ready all year and shows you what you can deduct.

AutoLog records each trip with start, end and GPS-calculated distance, keeps private trips separate, and exports a GoBD-compliant PDF for DE/AT/CH plus HMRC/IRS/CRA-compliant logs — offline, on your phone.