Begin with the current building-right agreement and all amendments. They should show the term, reason for expiry, compensation rule, building and possible calculation method. Side agreements and later changes cannot be ignored where they affect compensation or security.
Then compare the land-register position with the instruments. Relevant items include entries concerning the building right, mortgage instruments, priority information and indications of other rights in rem. An older extract may not show later changes, so the payment process needs a recent extract.
The file should also include documents about the end of the building right and the compensation. These may include notices of expiry, calculations, valuations, acknowledgements, payment demands and correspondence with creditors. They show whether the parties are working from the same claim and the same amount.
Where the building has been altered or extended, its description must match across the documents. The agreement, plans and calculation must refer to the same building state. The article on buying a demolition house and allocating building costs provides a related example of why the building condition should be described precisely.