Fahrtenbuch rules in Germany and Austria: what the tax office actually requires

A Fahrtenbuch only counts if it's complete, accurate and kept in the right form. Here's what the tax office checks — and how to not fail the test.

If you use a car for both business and private trips, the tax office gives you two choices: the flat 1%-rule, or a Fahrtenbuch (mileage log). The log usually saves money — but only if it survives scrutiny. A logbook with gaps gets rejected, and then you're back to the 1%-rule with back taxes.

What makes a Fahrtenbuch valid

1. It must be complete — every trip, business and private. A log with only business trips is not a log, it's a wish list.
2. Recorded in the right order and time — entries made at the time of the trip, in chronological order, not reconstructed at the end of the month. This is the number one reason logs get thrown out.
3. The right fields — for every trip: date, start and end odometer reading (or kilometres), start and destination, purpose, and — for detours — the route. Private trips can be a single block entry, but business trips must be itemised.
4. In a form that can't be changed afterwards — paper is bound, but a digital log must be tamper-evident. That's why GPS logs are accepted: they record the actual route, not your memory of it.
5. GoBD-compliant (Germany) — the log must be kept in a way that meets the GoBD rules for immutability and completeness.

The country matters

Germany applies GoBD, Austria applies EStG rules (and the Kilometergeld rate), Switzerland has its own requirements. A log that's fine in one country may not be in another.

The practical version

Log the trip when it happens (or let GPS do it), keep business and private separate, and export a clean monthly summary. The tax office isn't looking for perfection — it's looking for completeness, accuracy and honesty.

Bilal Shadid

Founder of The One Hand — builds privacy-first tools for solo businesses, freelancers, and tradespeople.