The landlord cannot simply charge what he likes for an apartment or room. Every apartment or room has a maximum rent, which is calculated using the Dutch national point system (woningwaarderingsstelsel). There is a system for rooms (shared kitchen and/or bathroom) and a system for apartments.
Rooms get a number of points, determined by the size and facilities of the accommodation. For apartments, the quality and location are also relevant. If you pay more than the maximum rent according to this points system, you are entitled to have your rent reduced by the Rental Tribunal (Huurcommissie). This is like a civil court that deals solely with housing rental cases. It is very easy to start a re-evaluation process and the costs for a process are only €25 (in 2017). If you think you are being overcharged for your rent, it is best to visit the Housing Helpdesk that will help calculate the points for your accommodation (the system is relatively complex and only provided in Dutch).
However, if your apartment/room has more than 141 points, or you have been paying €720.42 (Basic rent) or more for you rent and have done so for 6 months or more, you cannot reduce your rent. It is best to start a process within 6 months after your rental contract started. When the case is submitted to the rental tribunal within this timeframe the decision will have retroactive effect.
Another consideration should be the rent subsidy provided by the Dutch government to students living in certain conditions, the so called “huurtoeslag”. You can find all necessary info on that in this part of our finances section.