You must prove ownership by providing extracts from the land register (residential land register, hereditary building right register). The land register extracts must be certified. They must not be older than one month.
The declaration of commitment must clearly indicate the content of the public obligation assumed. If the building obligation cannot be clearly determined from the text alone, a certified extract from the cadastral map must be attached to the declaration of commitment; In its place, a certified extract from the city map or a site plan within the meaning of Section 2 (1) and (2) of the State Ordinance on Building Documents and Structural Inspection (BauuntPrüfVO) may also be used. In the case of special property, building, and boundary conditions, the building supervisory authority may require a site plan in accordance with Section 2 (3) BauuntPrüfVO. The areas affected by the building obligation must be marked by the cadastral office, a publicly appointed surveyor, or a surveying office in the extract from the cadastral map, the extract from the city map, or the site plan.