OT
Small correction.
Apart from Max Müller with his rented condominium, larger investors are usually subject to corporate tax and pay 15% CT + solidarity surcharge. Income from asset management also does not fall under trade tax.
So, I researched again. At the corporate level, corporate tax and solidarity surcharge apply, but not trade tax. At the owner level of the company, 60% of the personal tax rate applies under the partial income procedure. Assuming this is 42% + solidarity surcharge, or rather we should anyway consider the marginal situation, then from 100 EUR profit of the rental GmbH, 61.80 EUR net remain, correct? Without an intermediate rental GmbH, 42% + solidarity surcharge apply to the entire profit, so only 55.69 EUR remain.
Just out of curiosity. I actually concluded my last rental contract in a fairly large building (I estimate about 800-1,000 sqm of living space) at the time with a private person, so why actually, if the rental GmbH is cheaper? Of course, we can assume that the person renting out 900 sqm of living space in a good location probably paid the top tax rate.