Turnkey house - early acceptance possible?

I am somewhat confused about the assertive approach initiated by the GU. Due to the warranty risks, I actually didn't want to try that at all. Now our buffer is currently melting at record speed, so of course we are starting to consider whether this is a point to replenish the buffer.

I wouldn't do it; and I would ask myself which bottleneck is causing the GU the pressure.

that the risk of additional claims lies with the GU and not with us? I would have assumed that this would be passed on to us 1:1 and recalculated?

The payment of VAT is the responsibility of the GU. If he incurs an additional claim, he will pass it on (unless he only receives the claim after his billing with you has already expired).

I would have assumed that this would be passed on to us 1:1 and recalculated.

It depends on the contract arrangement with the contractor. The tax office will demand the 3% from him. If he does not have a corresponding clause in the contract itself or in his general terms and conditions, which you also sign, he cannot demand the 3% from you anymore. But whether you can pass on the 3% at all is, in turn, a question of your contract. It seems to me here as if the general contractor has this intention because he could earn 3% more here.

The risks have already been mentioned. In particular, the transfer of risk and the reversal of the burden of proof would discourage me. If something happens after acceptance (in terms of damages), the discussions will begin.