District Office assistance with cost calculation for residential area extension (40 m²)?

Hello,

I am planning to build an extension of about 40m2.
Now someone told me that the living area will be recalculated by the [Landratsamt] and that it is not cheap.
Unfortunately, the Google search did not yield anything interesting.
Maybe someone here can help me with what costs I might expect or how something like this is calculated.

Best regards
Benny

Hello Benny,

Maybe someone here can help me with what costs might come up for me or how to calculate something like that.

Aside from the fact that your question is more than lacking in information - why don't you ask the office first before reacting to " hearsay"?

Rhenish greetings