Private car for secondary occupation

Simply note down the amount of kilometres you drive for professional purposes. For each period, also note down the total amount of kilometres driven. This will allow you to determine the percentage of professional use. All costs incurred for your car (purchases, fuel, maintenance, repairs, insurance, car wash, etc.) are recorded using the same percentage of professional use. Normally, you will only know your actual percentage of professional use after one year, but for the first year you can use an estimate (and correct it at the end of the year if it differs significantly from the actual percentage of professional use).

Johan