The law introducing the mobility (or cash for car) allowance came into force in May 2018.
Employees with a company car that they can also use for private use can now give it back and get paid more instead without this income being treated by the tax and social security authorities as regular salary. The mobility allowance is calculated on the basis of the returned vehicle’s catalogue value and benefits from a favourable fiscal and social regime.
Read more about mobility allowance (Only available in FR and NL).
Source: SD Worx