Reader question: Which construction and financing features determine the partial application?
The advert says new build, the contract says free rent. That does not yet explain which parts of the Mietrechtsgesetz (MRG) apply. Especially easily confused are the year of a modernisation, the year of the building permit and the legal creation of your flat. For a reliable classification each of these details needs the appropriate evidence.
Compare the concrete facts
§ 1 Absatz 4 MRG lists different cases of partial application. These include buildings newly erected without public funds with a building permit issued after 30 June 1953. In addition there are specific factual circumstances for roof conversions, superstructures and extensions permitted after certain cut-off dates. For rental objects in condominium ownership a different threshold is given: new build of the building based on a permit issued after 8 May 1945. [MRG1]
Those are different approaches. For the first factual circumstance a funding statement is a central question of fact; it must not be replaced by the presumption that a privately offered house has always been privately financed. Likewise the designation condominium alone does not yet state which building permit the building is based on.
Follow the flat and the building separately
Our editorial recommendation: create a short history of origin. When was the building newly permitted? Was your flat created then or later through conversion, superstructure or extension? Which decision belongs to which measure? A mere renovation of the existing kitchen is not proof that the rental object was newly created under building law.
Please ask the offering or managing party for the actually claimed basis together with a suitable document reference. You do not have to form a legal opinion from a bundle of plans yourself. However, the documents should be specific enough that a specialist can follow the claimed classification.
Two fictitious listings
Flat A is in a building whose new build is based on a permit from 1960. Condominium ownership is not confirmed; regarding public financing so far there is only an oral presumption. For the factual circumstance of a new build not publicly financed this question therefore remains open.
Flat B was recently refurbished but is in a significantly older building. The new bathroom invoice evidences the refurbishment. It does not replace the original building permit nor proof of a later new creation of the flat. Therefore its fresh condition does not lead to a conclusive result on partial application.
The data are freely invented. In both cases the unclear prerequisite is named instead of estimating an age of construction from external impressions.
Partial application means a specific residual package
Paragraph 4 explicitly lists the provisions that continue to apply, including § 16b on the deposit and §§ 29 to 36 on termination of the contract. [MRG1] The statement "The MRG does not apply" can therefore be too sweeping for such a case. Conversely, a provision from the non-covered remainder must not be applied solely because it appears favourable.
This presentation does not replace the examination of the full exceptions in paragraph 2 nor of the special framework of non-profit building associations. For old contracts the respective transitional rules must also be assessed. The secure outcome of your preparation is a documented history of origin with a named path of examination. Rent level, clause validity and possible funding conditions are then checked on that basis.