Reader question: What area and which allocation key were used for my flat?
Your flat is recorded with a different area in the operating costs statement than in the available plan. That can raise a legitimate question. Before you calculate a new share, however, you need more than your individual square metre figure: the key used and the total area of the building associated with it.
First ask for the actual key
§ 17 Absatz 1 MRG generally bases the appropriate scope on the ratio of the usable area (Nutzfläche) of the leased item to the total leased items described there. It allows certain other keys agreed in writing for individual expenses and statutory special rules. Absatz 1 a deals with apportionment by consumption under particular conditions. [MRG17]
Our editorial recommendation: therefore ask not only “How large is my flat?” but also “According to which key was this specific cost item distributed?” The same letter can contain items with different bases. First check whether the MRG framework shown is applicable. [MRG1]
The denominator is part of the review
Under the statutory principle, leased items used by the landlord or not let despite being lettable also count towards the reference area. [MRG17] An empty flat is therefore not simply removed from the denominator so that the remaining households carry everything.
A simple calculation example illustrates the significance: 60 square metres out of a total of 600 make ten percent. If, without a valid reason, only 500 are used, twelve percent results. Those are freely chosen numbers, not a statement about a specific building. The legally correct reference area must first be determined.
Not every area from the listing is usable area under this standard
Absatz 2 defines the usable area. Among other things it excludes open balconies and terraces and certain cellar and attic rooms unsuitable for residential or commercial purposes. It contains its own temporal rule for structural changes made by the tenant to the interior. Absatz 3 distinguishes between measured area (Naturmaß) and, for buildings approved later accordingly, the approved plan including exceptions. [MRG17]
Therefore do not automatically add your terrace to the internal area and do not adopt any arbitrary online living-area formula from Germany. Disclose the plan designation, approval status and actual deviation. For disputed measurements an appropriate expert survey may become necessary.
A hypothetical reconciliation with three sources
In Farah’s case the contract states 58, the statement 62 and an old listing 70 square metres including outdoor area. She submits the three figures separately. The administration should first explain which rooms and which plan underlie the 62 square metres and which total house area was used.
Farah does not replace the value unilaterally with the smallest number. Only the appropriate statutory area basis makes a correction verifiable. A changed area approach can also affect more than a single annual statement; period and possible claims must be examined separately.
Conclude the enquiry with one item
Combine the discrepancy, your supporting document, the share used and your specific question. If asking for a change, request a comprehensible corrected calculation. The article does not decide an individual rent reduction due to a contractual area discrepancy. It addresses the other task: to recognise whether a particular building cost item was distributed on a documented and appropriate area basis.