183-days rule is NOT a thing in germany for corporate taxes, and I think it is not in income taxes either. It may be an indicator, but it is not a hard proof. Important is, where you have your social life set up ("Lebensmittelpunkt"). That is, you can reside more than 183 days abroad, but if you have a family, golf club membership, permanent residence, your stock brokerage account etc. still in germany, you still count as a german tax resident. There are no hard laws with X days around it, german law revolves a lot around that "Lebensmittelpunkt" which will be decided on a per-case basis.

Its a little bit more complicated:

https://www.vlh.de/wissen-service/steuer-abc/183-tage-regelu...

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.