Your servicekosten statement was due by 30 June: dig out the 2025 one, because any overpayment is yours

In a Dutch rental, the servicekosten line on your monthly bill is not the final price. It is an advance, a voorschot. The real figure only appears in the yearly statement, the afrekening, where the landlord takes what the building actually spent over the year on heating, water, cleaning, stairwell electricity and management, divides it across the flats, and sets your share against what you already paid in advance. The Huurcommissie's own policy book on service costs states that the landlord must deliver that statement within six months of the end of each calendar year. Turned into a date, the 2025 service costs were due to reach you by 30 June 2026. It is now 31 August, so if that sheet has still not arrived it is two months overdue. source 1

Once you have it, the subtraction is a single step: your monthly advance × 12, or the months you actually lived there, minus the real cost allocated to your flat on the statement. A positive difference is money the landlord owes back to you; only a negative one means you top up. Most people never run it because they assume the advance was the real price, but the advance is the landlord's own estimate, and an estimate set high is a year of your money sitting in someone else's account. The same policy book also names a category that may not be in there at all: in buildings on a WKO system, which stores heat and cold underground, the capital and maintenance costs of that installation may not be passed to the tenant through service costs. Only the variable consumption may. That line is worth hunting for specifically. source 2

If the statement never arrives, or you disagree with how it was split, the window is longer than most people assume. The policy book cites article 7:260 of the Civil Code: a tenant may bring a request within twenty-four months counted from the day that six-month deadline expired, which is two and a half years after the calendar year ends. The worked example in the book puts 2024 costs at 30 June 2027, and the same arithmetic puts 2025 costs at 30 June 2028. There is one more wrinkle: where a supplier bills on a non-calendar year, August to August for instance, the deadline shifts to the end of the calendar year in which that deviating period ends, plus six months. So the useful move today is not to chase, it is to put those two dates in a calendar and multiply out your own 2025 advance. That product is the baseline you are entitled to hold the statement against. source 3

• The advance is not the price: the monthly servicekosten is a voorschot, settled by the yearly statement.
• Landlord deadline: within six months of the calendar year ending, so 30 June 2026 for the 2025 costs.
• Your sum: monthly advance × months lived there, minus the real cost allocated to your flat; a positive difference is owed back.
• WKO buildings: the capital and maintenance costs of the installation may not go into service costs, only variable consumption.
• Challenge window: 24 months from the day the six-month deadline expired, so 30 June 2028 for the 2025 costs.
• Non-calendar billing periods shift the deadline to the end of the calendar year that period ends in, plus six months.

Hokimi field note: check first whether the period printed at the top of the statement is a whole year, because a good share of disputes are really two billing periods being read as one.