The landlord is obliged to break down the rent into bare rent and service costs. If the landlord charges an all-in price, it is difficult to check whether the rent is too high or not. If he does, you first have to formally ask him to split the rent. You can do this for example by sending a (registered) letter. If he refuses or does not respond, you can start a procedure with the rent assessment commission (huurcommissie) to enforce a split.
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