Only two very limited vehicle categories do not pay toll. Viapass differentiates between vehicles outside the scope of the kilometer charge and exemptions.

• the vehicles that fall outside the scope of the kilometer charge may optionally request to be recognised as such.
• a limited number of vehicles that are exempted and require an exemption beforehand. They concern only the following categories:
  • Vehicles used exclusively by the army, civil defense, fire department and police which are recognizable as such.
  • Vehicles especially and exclusively equipped for medical purposes and recognizable as such.
  • Vehicles of the agricultural, horticultural or forestry type using public roads in Belgium in a limited way and used exclusively for agriculture, horticulture, fish farming and forestry.

The general rule that determines who pays toll:

• Category N vehicles (= HGV; see vehicle documents) fall outside the scope of the kilometer charge if the Gross Vehicle weight (= GVW) is less than or equal to 3.5 tonnes.
  1. Vehicle category N1 is less than or equal to 3.5 tonnes GVW and falls outside the scope of the kilometer charge. The only exception are tractor units of category N1/BC, provided that the tractor unit weighs more than 3.5 tonnes when you add up the weight of tractor unit and trailer (= GVW towing). See also box F3 on the vehicle documents.
  2. Categories N2 and N3 are generally heavier than 3.5 tons, unless the N2 has been downrated to a GVW ≤ 3.5 tons and is therefore equated with category N1. See the box F2 on the vehicle documents.
• Vehicles of category M on the vehicle documents are intended for passenger transport and therefore fall outside the kilometer charge. Common examples are most buses and passenger cars.