Building a duplex and renting out a part - experiences

Maybe it is also crucial whether you rent out an anonymous "living toilet" in an apartment building or a residential unit in a [DH]? I can't really report anything negative from my own experience or from landlord experience within the family. However, we neither squeeze out the last euro nor are we super picky ;)

2 property managers who together manage over 1000 units

Troublemakers exist in all areas.
He is not looking for 1000 great tenants, ONE is enough.;)

Thanks first of all to everyone for the input. I am aware that there are bad apples. Tendentially, the area / the equipment would be such that you don’t get the "Rtl2 Klientel". As already mentioned at the beginning, possibly also the parents. I was more concerned with the experience of financing such a thing :) That’s why also the subforum as the basic discussion :)

We are working on a property that offers the possibility to build a duplex and rent out part of it.

Trying to build wealth by playing landlord with a lot size of "1 residential unit" and even building it new are already three mistakes at once – with borrowed money even four. Only victims of crooks who spell "investment" and/or "advisor" with an "h" and tell trusting milkmaids tall tales, like the Easter Bunny would bring the Christmas presents, do that.

When the parents move in, it is certainly the best deal tax-wise. From the beginning, there must be 2 separate units, land register, declaration of division, and loan, invoices.... If it is done well, there will be a large tax refund. However, there is no speculation tax upon sale. The profit must be taxed as income if it was rented out. A good tax advisor can certainly also manage to make it tax-free.

I was more interested in the experience of financing such a thing :) Hence also the subforum rather than the basic discussion :)

Investing capital in a newly constructed house is a disaster from a return perspective. Therefore, (since I do not speculate on rising prices but rather consider the effort with tenant changes and the ratio of rent to acquisition costs) it is absolutely not my thing. Calculate it for yourself.