49M Singapore -> Munich Germany

Hi

As the title intended, I am a 49M Singaporean who intends to move with my wife 47F British to Germany next year. We have a 5 yr old kid who we wish to send him to a school there. I will be going under my wife via Blucard visa. I don’t have the intention to work there for the next few years as I have a HDB flat which I will rent out and that will be my primary source of income.

I would like to know if I still need to declare such income to the Germany authorities if I do not intend to work there. And if there are any other hurdles I may have to overcome for other Singaporeans who have immigrated to Germany with their spouses?