Address registration: the beli karton for foreigners
Address registration, locally called the beli karton or white card, confirms that the police know where you live. You cannot apply for a residence permit without it, so a landlord who will not provide it is of little use to someone moving here.
What it is
A foreigner in Serbia has to be registered at the address where they live. The police issue a confirmation of registration, and that is what people call the beli karton. In a hotel the hotel does it, in a rented flat the landlord or you yourself.
Who does it and when
A hotel, or anyone who provides paid accommodation such as short stays, registers the guest within 24 hours. With a long-term rental, the landlord either registers the tenant or gives the tenant the lease so the tenant can register within 24 hours. It is done at the police station that covers the address of the flat, or at the police department for foreigners.
If the landlord gives you the documents
You can register yourself. You need your passport and the document that lets you live in the flat, usually the rental contract. The landlord has to be ready to sign it.
Why you need it for a residence permit
For a temporary residence permit the police ask you to prove your address: a rental contract or a statement from the landlord agreeing to have your address registered. If the landlord refuses, you cannot apply with that flat.