So OP has to clarify on both layers: natural person himself, legal entity, and the relation between them. And the result is affected by the questions OP raised?
If you are a shareholder director (“Gesellschaftergeschäftsführer”) you have a contract but are still treated as self employed for most laws. The 183days rule does not apply in that case.
That articles refers to employees (Arbeitnehmer) which is something completely different.
Yes, and if you are a company owner, you usually have a contract between you and yourself? (https://www.hensche.de/Rechtsanwalt_Arbeitsrecht_Handbuch_Ge..., "Geschäftsführeranstellungsvertrag")
So OP has to clarify on both layers: natural person himself, legal entity, and the relation between them. And the result is affected by the questions OP raised?
If you are a shareholder director (“Gesellschaftergeschäftsführer”) you have a contract but are still treated as self employed for most laws. The 183days rule does not apply in that case.