switching to another insurer and filling in a complete questionnaire again why

Every insurer has its own acceptance questionnaire

This is not because the previous insurer did anything wrong. Every insurer determines for itself which questions it asks during acceptance, in what order and with what supporting documents. There is no shared standard between insurers, and there is also no obligation to take over the acceptance file from the previous insurer. For a liability insurance, this usually means again: business activities, turnover, number of employees, claims history and sometimes the measures you have taken to limit risks.

What does help: the source data are the same, only the format differs. The statutory name, the business address and the sector in which the enterprise operates are already fixed from registration with the Chamber of Commerce. The number of employees and the annual turnover may change slightly since the previous list, but cannot be looked up again. If the new insurer asks a question about an existing liability insurance, it is often a question about the previous policy, not the new one — pay attention to that distinction when filling in.

No shared register, but the same source data

That every insurer uses its own list and its own acceptance process follows from the absence of a shared acceptance standard between insurers: there is no law that requires insurers to ask the same questions or to take over a previously given answer. What is fixed, however, is the basic registration of the company itself: name, legal form, place of establishment and activity are registered in accordance with the Trade Register Act 2007. Those data are the source from which you can draw for every new list, even if the format of the question varies each time.