Build/buy a house, what do you think?

Here, amortization (for tax purposes) is penalized. That is why only a few do it. The (first) mortgage is almost never repaid.

now I know why [der schweiz] is doing so well :)

Hi Thorsten,
At this point you need to hire a financial expert. Ideally two, so you have a comparison. But from what I can roughly see, this can work well.
All the best and good luck
Kurt

Hello again,
I was at the financial advice today: For the entire 300k, we went through several scenarios with KfW,... The current favorite would be the attached offer. 910 euro installment with 230,000 loan and residual debt 150,000. Repayment would be with a 125,000 building savings contract and at least 25,000 prepaid beforehand. There is a 1-year free provisioning period. I was surprised by the fact that repayment can only begin once the loan is fully drawn? I didn’t know that yet. Assuming the construction takes 1.5 years, then I only pay interest during that time and cannot repay anything, and on top of that, I lose 1.5 years of interest rate lock. Well, if that’s really how it is, I didn’t know that... what do you think?

Assuming the construction takes 1.5 years, then I only pay interest during that time and can't repay anything, and on top of that, I've "wasted" 1.5 years of fixed interest period. Well, if that's really the case, I didn't know that... what do you think about it?

Yes, that's how it is. In return, you secure the good interest rates at closing... ;)

Yes, that's true, but effectively I don't have 15 years to repay. But you can't change it anyway.