Am I creditworthy as an individual in the following situation?

Just as feedback, in case people are in a similar situation as I am and are looking for a current comparison:

1. Offer:

150k at 2.52% over 25 years - bank

50k at 1.55% over 10 years - KFW 124

Mixed interest rate 2.29% - 768 € monthly

Sounds pretty good to me. The KfW loan has a remaining debt of 33k after 10 years. At this time, a building savings contract of 20k at 1.75% will mature, which I am currently contributing to.
The large loan still has 46k outstanding at the end, but at that point I still have 15 years until retirement anyway...

I am now looking forward to the GU’s offer...

Replace the KfW 124 with a 50k€ from the financing bank, as you currently get it 0.2% cheaper at your bank. The 124 offers you no advantages. Otherwise, I cannot assess the interest rate of the large loan.

Yes, I had the same thought that a bank loan might be more suitable. Not only because of the interest rate but also possibly because of a longer term concerning the [Bereitstellungszinsen].

Exciting, exciting. If you can realize this with the budget, then hats off. But if I look at the land price, the world seems to turn a bit slower for you overall. Many are currently heading more towards 400€/m² instead of 40€/m². You should try to plan some buffer in somehow. At the moment, I wouldn't know where it would come from, since equity and your salary don’t leave much room and the 200k€ could already be tight. But especially from that perspective, you need to have reserves in the background, because doing the work yourself can quickly become expensive: - You get injured or sick and have to have it done after all - The helping hands aren’t or aren’t that numerous and it leads to longer construction time and double burden (loan + rent) - It gets more expensive because you couldn’t calculate everything exactly or simply forgot something as an amateur. 10-20k€ can quickly hurt badly and jeopardize your entire financing. Therefore, it would be important to possibly bring your girlfriend, parents, etc. on board as a last resort. The worst-case scenario would be if the loan falls through shortly before or after the completion of your house because the refinancing doesn’t work out and you then have to sell the thing off cheaply because there is no market for real estate in the area.

The girlfriend is also financially (secured) involved, but everything should be in my name. We can avoid credit + rent, we can stay with the family for a short time.

The most realistic problem I see for us is forgetting / underestimating a position ...