**The tandem axle counts as two axles, the tridem axle counts as three axles. Lift and retractable axles are always taken into account, regardless of whether a vehicle axle is being used or is lifted during transportation, in other words has no road contact.
The road user subject to toll must prove the accuracy of all relevant data for toll collection when requested by the Federal Office for Goods Transport (BAG) by showing appropriate documents (Section 5 of the German Federal Trunk Road Toll Act (BFStrMG) in conjunction with Section 7 of the German Truck Toll Regulations).
For all trucks registered in Germany, the emission class can be proven by the vehicle licence, part I of the vehicle registration certificate or the vehicle tax document (§ 8 of the German Truck Toll Regulations).
For vehicles registered outside of Germany, time-based presumptions apply if the emission class cannot be proven in another way, in particular with documents attesting the fulfilment of certain environmental requirements in ECMT transport (European Conference of Ministers of Transport), (Section 9 of the German Truck Toll Regulations).
The road user subject to toll is responsible for demonstrating and proving all data relevant for toll collection. Failure to provide proof will be penalised with a fine.