Are the ancillary construction costs calculated correctly?

Soil investigation report

including resulting consequences for the foundation of the building

I believe the OP no longer wants to hear about what other costs are coming his way [KOMMPLETT].

There is a long list of things that you are not aware of and that are not mentioned to you by the [GU] because they are so-called "bauseits," meaning your problem. There are entire threads here where this has been compiled. Highly recommended reading.

I think the OP doesn’t want to hear anymore about the costs he still has to face

Yes, why not?

There is a long list of things that you don’t have on your radar and that won’t be mentioned to you by the general contractor either, because they are so-called "bauseits," meaning your problem. There are whole threads here where this has been compiled. Highly recommended reading.

I have to say that the house is being built by a construction/planning company. They handle the planning, supervision, and coordination. They also take care of the house connections, etc., until everything is finished... or turnkey, in other words. Everything from a single source. I just wanted to inquire here once what I can roughly expect and if I have forgotten anything so that I can already prepare a budget for the loan. My bank also roughly knows many things, but only very roughly. Hence my question(s) here. That I need a kitchen and that I won’t have much garden space with about 400 sqm is already clear to me or should be clear to everyone. That was the goal anyway, that I don’t want much to do with garden maintenance now and especially when I’m older. For the interior, carport, garden shed, etc., I have also calculated from the very beginning. I mentioned the topping-out ceremony here specifically, because some people add everything up but exactly forget that and quickly spend 1000 euros for such a celebration.

They do the planning, support, and coordination. They also take care of the house connections, etc., until everything is finished... or turnkey. So everything from a single source.

Then take good care of the contract. It is not standard that really everything comes from a single source or is included in the final price.