Turnkey house - early acceptance possible?

Depending on what "in advance" means. In advance would actually be if I make the agreement in November and the agreed partial acceptance takes place in December. Or not, that is certainly questionable.

In the end, it seems safest to me to declare the final acceptance of the nearly completed house in December and additionally agree with the general contractor that I take over the still outstanding services (installation of doors and sanitary fixtures). Of course, I would bear the costs already incurred by the general contractor through ordering and planning or "offset" them with minor defects.
That should not be legally objectionable if the contract is mutually amended in terms of the scope of services.

that I take over the still outstanding services (installation of doors and sanitary objects). I would of course bear costs already incurred for the general contractor through ordering and planning, or "set off" against minor defects.

But with that you are making a loss when it comes to the VAT on 20,000. €600 savings, in return a few bucks for sanitary and doors, where you have to pay proportionally more if you have them installed independently.

The savings should be somewhat larger, as the 3% "more" VAT is calculated on the total amount, so (estimated) €300,000, meaning €9,000 more VAT to pay. For that, you can install a nice golden toilet ;)

also (estimated) 300,000€, so 9,000€ more

slowly I understand ;) well, weigh everything up. What Corona is good for.., :cool: Have you already approached the GU?

Exactly, that is the goal. We are expecting around 8500.

I want to approach the [GU] tomorrow. Since I am a complete layman, I wanted to get advice from the community here beforehand. I have to be prepared for almost all eventualities, and there are clever people here who have more expertise than I do.

It's best to also get advice from a tax advisor, since even we here are just laypeople. ;)