If you are moving abroad for more than 8 months, you must deregister with the municipality. You can deregister in two ways: online or at city hall. You can only deregister online if all residents of the address are moving abroad at the same time. If you live with several other people at the same address and not everyone is moving abroad, then only the people who are moving with you need to visit city hall in person. This also applies to children under the age of 18.