Originally Posted by
mfkne
You only tap it when you enter the station or as you approach the platform or on the platform itself, depending on the station. At Schiphol you touch in and out before you go down to the platform, at Amsterdam Central you touch in and out as you enter or leave the station.
I would be going between Leiden & Haarlem and later between Haarlem & Hoofddorp.
Two years ago when I only took the train between AMS & Centraal Station as well as Hoofddorp and AMS (a very short ride), I didn't tap anything. Is the rail system different now?