You are obliged to inform and seek the consent of your landlord (or the building management) regarding a sub-lease.
If none of the rejection reasons stipulated in law apply, the sub-lease must be approved.
Ideally, you should send a copy of the contract with a request for approval. The sub-lease contract contains all relevant information: rent, rental period, details of the sub-tenant, etc.
This transparency coupled with an acceptable reason as to why you wish to sublease your apartment will significantly improve your chances of receiving consent without any problems.
If you create your sub-lease contract via the tempoFLAT online contract tool and then send it to the landlord, he or she will see that you are sub-letting your apartment through us in a proper manner, which will generate additional confidence and goodwill.
If you sublet your flat to a third party without the consent of your landlord, you run the risk of your landlord commencing proceedings for an injunction or terminating your lease for the flat entirely.
We recommend that you inform your landlord in any case, in order to prevent any bad feeling and to avoid any awkward meetings between the sub-tenant and landlord.
No responsibility is taken for the correctness of this information.
[Link] Sample templates for obtaining the consent