Transfer of lease agreement after purchase

No, the rent is due to you as soon as the economic transfer has taken place. You define this in the purchase contract, usually with the payment of the purchase price. From then on, you are also responsible for the ancillary costs/public charges.

Correct, the rent is due to you from the date of the economic transfer.

However, you may only terminate once you are registered as the owner in the land register.

ok, thank you for your help

By law, I believe it is 3 months from 2002 onward.

Maybe for the tenant, but certainly not for the landlord!! Personal use usually 12 months..

No, definitely not.

3, 6 or 9 months, depending on the rental period.
§573c Building Code

0-5 years rental period: 3 months

[*]5-8 years rental period: 6 months

[*]from 8 years rental period: 9 months