Every year, on the first of July, your landlord is allowed to increase the price of the basic rent and the service costs. If your landlord will increase the prices, he or she has to inform you before the first of May.
The base rent is the rent without the service costs. Based on the Dutch law, the increase of the rent for a room has a maximum of 3,1 percent. For a studio and apartment, the increase is based on the yearly income of the tenant. If your yearly income is below €42.436, the average increase of the rent will be 4,1%. If your yearly income is above the €42.436, the average increase will be 5,6%.
Service costs cover the costs of gas, water, and electricity. Some other examples are the costs for cleaning, repair work, furniture, upholstery or administration costs. Every year, your landlord will send you an overview of all the costs. If the costs devere from the costs you paid the previous year, your landlord can increase or decrease your rent.
If you would like to have more information about the increase of the rent, please check the website of the Dutch Government (original source).