For how many years of fixed interest period would you currently finance?

Construction prices have indeed risen massively. We have been considering this for almost 4 years, but only this year were we actually able to decide (mainly because we only now found a nice plot of land that we like due to its location, elevation profile, and price) and as a result, we have to pay quite a bit more than we would have had to a few years ago. Okay, the equipment (e.g. energy level) has also improved, but by no means to the extent that the price has increased.

We originally planned to finance like this: 10 years KfW, 15 years for the majority, and 20 years for the rest. Then we realized that the 15 years would have cost more than 0.8 percentage points more than the 10 years (due to a special offer), and the 20 years would have been even more than 1 percentage point more expensive with this component. We’d rather put the interest savings into repayment. And we also gave up on the 20-year residual and did everything over 10 years, since with a uniform term regarding the bank, one is much more flexible (no commitment to the institution that holds the long-term component).

However, for us, special circumstances made the decision to take the 10-year risk significantly easier:
- The KfW loan is fully repaid after 10 years (shortly before the fixed interest period ends, an old home savings contract with over 4% interest credited will mature, which is almost perfectly timed for the residual debt of the loan component, as it was recently allocated, and from then on the 10-year period begins). The resulting freed-up monthly rate is then "extra" and can be used, if needed, for the repayment of the follow-up financing of the remaining components.
- 100k are secured via existing home savings contracts, which are already saved to the extent that I can bring them into allocation with minimal monthly amounts by mid-2028. Home savings loans are subordinated and possible, securing a loan of 100k minus deposits at 2.35%, in case the interest rate for the follow-up financing is higher. Of course, the remaining savings rate for the home savings contracts could also be put into repayment, but that doesn’t make much difference, and the risk-reward ratio is clearly better with the remaining home savings accumulation despite the low credited interest rate.
- In case of doubt, we still have investments in reserve, which could be cut or liquidated if the nominal interest rate of the follow-up financing exceeds the return on the investment. With the current financing, the return on our investments is considerably higher even after taxes, which is why we haven’t touched them.

But feel free to ask again in 2028 whether I regret only having fixed the rate for 10 years...

And no idea what kind of special offer that’s supposed to be, but a 0.8% surcharge for 10 to 15 years is out of the question. It was probably the 15 years that were bad rather than the 10 that were good.

Or the 15 years standard and the 10 years a special offer for a limited group of people.