Notice the order things actually happen in. Someone gets a car, starts running work errands, and only when the first payday nears do they ask how to claim the reimbursement. By then one step has already been skipped — and it decides whether the reimbursement is tax-free at all.
The first step is the agreement
Before the first work trip there must be a written agreement between employer and employee granting the right to use a personal car for work. It can be an annex to the employment contract or a separate employer decision — the form matters less than the document existing and being signed. Without it, even a flawless logbook won't help: the reimbursement can be paid, but it isn't tax-free. That one piece of paper is exactly what gets forgotten most often.
Only then comes the logbook
With the agreement in place, the logbook does its job. Reimbursement is paid for actual work kilometres — €0.50/km, up to €550/month. Each trip needs its date, route, odometer readings and purpose; what exactly is required is set out in the guide. The idea is simple: the agreement grants the right, the logbook sets the amount.
Where it usually breaks down
The most common mistake is signing the agreement after the fact — once the MTA is already asking. The second is mixing private and work trips: if a single drive serves both the grocery store and a client, it isn't a work trip. The third is a reimbursement that lands on exactly €550 month after month with no variation; nobody drives that regularly, and an auditor knows it. None of these is hard to avoid if records are kept as you go, rather than from memory at month-end.