Mixed property: Advantages or disadvantages? - Experiences?

hello,

if you can finance the property without the rent, then why not. if you depend on rent, then don't do it.

This should leave a good contribution for your own apartment even after taxes (which you can somewhat control yourself if you are creative).

exactly: because much of the building material you install will hardly be attributable to your apartment or commercial unit by the tax officer. (Electricity, water, etc.) That means with a clever tax advisor, you hardly ever pay taxes there ;-)

The problem is not the tax advisor, the problem is often the client.

If the sanitary invoice says "Bathroom 1st floor bathtub," then as a tax advisor you cannot allocate that to the ground floor. No matter how much the client scribbles on it that it was for the ground floor, it simply won't be credible.
If it says bathroom renovation ground floor and 1st floor, then you divide the invoice according to square meters.
If the invoice says bathroom renovation ground floor, then you can directly assign that to the rental.

So always pay close attention to what the craftsman writes on it.