Axles, weight class and empty runs: where the German toll invoice gap appears

The CO2 class is the biggest, but not the only, source of German toll invoice discrepancies. A second group relates to how the vehicle itself is defined.

Axles aren't counted the way it looks

The rate depends on axle count, and the counting rule is simple but not obvious to everyone: a tandem axle counts as two, a tridem axle as three.

A five-axle, over-18-tonne combination is billed at 34.8 ct/km, a four-axle one at 32.4 ct/km. The 2.4 ct/km difference at 80,000 km a year is about €1,920.

The problem arises with combinations of changing composition. Drive with a five-axle trailer, uncouple it, and continue with three axles, and the axle count changes mid-trip. If the on-board unit's setting isn't changed, part of the trip is billed at the wrong rate — sometimes in the client's favour, sometimes not.

An incorrectly stated axle count is also an administrative offence, carrying fines for both the driver and the company. So it's not just a money question, it's a compliance one too.

Weight class comes from documents, not cargo

A second common assumption is that an empty run costs less. It doesn't.

The weight class is determined by the technically permissible maximum mass stated in the vehicle documents, not the actual cargo. An empty tractor unit is billed at the same rate as a fully loaded one.

That means reducing empty runs is a cost question, not a rate question — the invoice will show the full rate either way.

The chargeable network is wider than most people think

The toll applies on all federal motorways and all federal roads — a network of about 51,000 kilometres. Since 1 July 2024, it applies to all vehicles from 3.5 tonnes of technically permissible mass.

The practical consequence: leaving the motorway for a federal road saves time, not the toll. Route planning based on the assumption that federal roads aren't chargeable gives a false cost basis.

What to look for on the invoice

Three things you can check even without special tools.

Whether the billed axle count matches the registration documents on every line. Whether the same stretch was billed twice on the same day. Whether there are lines on days the vehicle wasn't operating.

The last point is the hardest to check, because it needs a separate source of operating days — tachograph data or transport management system records. Without it, that check can't be done.

Zero-emission vehicles

A separate note for fleets considering electric tractor units: zero-emission heavy vehicles are exempt from the toll until 30 June 2031. A partial-charging rule planned for 2026 was withdrawn in November 2025 before it took effect.