If a change of address is due to a change in corporate personality, an official letter has to be sent or a new user agreement has to be concluded. This legal obligation arises in particular if:

• the company name changes
• a change of corporate structure, for example from limited liability company (GmbH) to a stock corporation or plc, results in a new legal entity, although partners or shareholders are identical with the former partners
• there was a corporate takeover, resulting in a change of partners or stockholders and consequently of corporate identity