If you will be staying in Germany for more than three months, you (and the members of your family) will need to register at the local Residents' Registration Office within one week after arrival. If you move to new accommodation within Germany, you must register at your new and deregister at your old place of residence. You must also deregister your residence status when you leave Germany.
In order to register, you will need to present a valid passport or personal ID document and written confirmation (Wohnungsgeberbestätigung) from your landlord or their agent that you will be resident at the specified address.
About six to eight weeks after registering, you will be sent a letter with your tax identification number (TIN). If you have an employment contract with Saarland University or one of the on-campus research institutes, please communicate your TIN to the university's Human Resources department.