If you travel in commuter trains within the HSL Area at night between 02.00 and 04.30 (Mon-Sun), a one-way night fare is collected. 
 

Weekend night ticket inspection at Helsinki railway station

On week-end night services tickets of passengers boarding all commuter trains are checked before boarding the train at the Helsinki railway station. Friday and Saturday nights from 23.00 hrs until the end of the night services, the tickets are checked at the departure platform gate before boarding the train. The purpose of the platform-gate ticket inspection is to improve customer security.

Passengers have to present a valid ticket at the gate before boarding the train when using night services as fences are placed in areas leading to the commuter train platform. There is a card reader at the gate for passengers using a Travel Card. We recommend passengers arrive in good time at the gate ticket inspection in order to avoid delays.