Nebenkosten Distribution Key: Why Most Costs Are Split by Square Meter

Anyone reading a Nebenkostenabrechnung (utility cost statement) for the first time asks the same question: what rule decides who pays how much? The answer is set by law, and it depends on whether a cost type can actually be measured.

The legal default: living space

If the Mietvertrag (rental contract) doesn't set its own distribution key, living space (Wohnfläche) automatically becomes the standard. Under § 556a BGB, Betriebskosten (operating costs) must then be split in proportion to each tenant's share of the building's total living space. Costs like property tax, building insurance, or caretaker fees are almost always divided this way, because they arise regardless of how many people actually live in a given apartment.

When consumption is billed instead

For cost types that can be metered, the law takes a different approach. For heating and hot water, § 7 HeizkostenV (the German Heating Costs Ordinance) requires that at least 50% and at most 70% of costs be billed according to actually recorded heat consumption, measured through heat cost allocators or heat meters on each radiator or heating unit. The remainder is still split by living or usable space. This combination of consumption-based and area-based billing is mandatory nationwide for heating costs, regardless of what the rental contract says.

Why some costs are billed per person

Water and waste collection are often split according to the number of people registered in a household, when there's no individual water meter per apartment. This is legal because consumption for these items typically correlates with household size. Landlords can set this key in the rental contract, as long as it doesn't disadvantage the tenant compared to a floor-space split.

What this means for your own statement

If you want to check whether the key used in your Nebenkostenabrechnung is correct, start by checking the Mietvertrag for an explicit agreement. If there isn't one, living space is the automatic default — except for heating and hot water, where consumption-based billing under the HeizkostenV is mandatory. If your statement doesn't follow this, you can question the distribution key used and ask for a correction.

Costs also differ depending on which category they fall into — see our utility cost breakdown for typical figures per cost type. If your landlord raises the advance payment, our Nebenkosten check explains when an increase is actually allowed. And our rental contract guide covers what the distribution key means for your own lease clause.

Frequently Asked Questions

What distribution key applies to Nebenkosten if the rental contract says nothing?

Without an explicit agreement, living space automatically becomes the distribution key under § 556a BGB.

Does heating always have to be billed by consumption?

Yes — at least 50% and at most 70% of heating and hot water costs must be billed according to recorded consumption under § 7 HeizkostenV, with the rest split by floor space.

Can a landlord bill water by the number of occupants instead of floor space?

Yes, if there's no separate water meter per apartment, billing water and waste collection by occupant count is allowed, provided it's agreed in the rental contract.

What can I do if the distribution key on my statement looks wrong?

Check your Mietvertrag for an agreement first. If there isn't one, or the statement doesn't follow the legal default, you can challenge the key used and ask your landlord to show how it was calculated.