L-Bank Z-20 limited residential area with basement

Addendum - In addition to the escape routes, structural considerations must be taken into account: This already costs quite a bit of money at the beginning to create living space in the basement later on (regardless of the equipment with electricity, heating, plaster, etc.). Retrofitting is only feasible in case of acute space shortages, as it is sufficiently expensive.

In another thread it was hinted how much heat an inverter emits -> perfect for drying clothes. So a large drying and technical room is a nice idea to optimally use the waste heat.

For the use of waste heat, you include the room in the heat recovery of your controlled residential ventilation system.

And what if the OP submits an application for reclassification of the basement to the building authority in a few years? He pays a few bills and everyone is happy, right?

No, that’s not the case. Those are simply malicious accusations from you.

Fraud malicious accusation, fraud with delay clever exploitation of legal loopholes?

I don’t see it that way. With taxes, you also have an advisor who gets the best out of it for you. With a 250cm basement with underfloor heating, no one seems to complain either.

The abuse of legal structuring options is specifically dealt with by §42 AO.

A clever use of loopholes is not fraud even if many here apparently do not like it. With parental allowance, optimization is also done in advance to get the maximum out of it. Or with [KfW300]…

I still thank everyone for the input.

A clever exploitation of a legal loophole is not fraud

That is true, but here it is questionable whether a loophole is being exploited or something illegal is being done.
A later reclassification might be possible, but what have you gained if you have to pay retroactively? Also, an authority could say no, in which case you have sunk the costs for the preliminary work for the residential permit. Then you have exploited something with a lot of work and in the end it does not pay off.

I simply do not see the value from a pragmatic point of view.