KfW153 loan immediate repayment - prepayment penalty?

Online calculators spit out something around 1,500 EUR prepayment penalty for me

That is complete nonsense (not the calculation, but that you are calculating now). If there is a significant movement in the interest rate market until the special repayment, it might be that you pay €15,000 or maybe even get out without any cost. That is purely crystal ball reading. BUT: In my opinion, it pays off.

Where is the catch?

That actually nobody has that much money lying around

Well, if the prepayment penalty is too high, I'll just continue paying off the loan as usual. Now I just have to find a bank that grants the [KFW loan] without an additional bank loan (not so easy). And an energy consultant that isn't too overpriced.

Now I just need to find a bank that grants the KFW loan without an additional bank loan (not so easy).

Good luck! I don't know any bank off the top of my head either - we don't do it either, as it's not really worthwhile.

Well, if the prepayment penalty is too high, I'll just continue repaying the loan normally. Now I just have to find a bank that grants the KFW loan without an additional bank loan (not so easy).
And an energy consultant who is not too overpriced.

Is it somewhere in the fine print that you then have to repay the subsidy proportionally?

Is there anywhere in the fine print that you then have to repay the subsidy proportionally?

Thank you for the hint, I will go through it. But so far, I have only found one clause stating that the repayment subsidy at the time of crediting must not be higher than the remaining debt (which would then be capped accordingly). But I can safely leave the remaining debt above the repayment subsidy; the early repayment including the prepayment penalty is not urgent (if it is even better than repaying normally at the end). Does anyone else think of any other pitfalls?

we don't do it either, as it is not really worthwhile.

My worst-case calculation comes to well over EUR 10,000 – is that an amount that is really not worthwhile, or am I miscalculating somewhere? Or do you mean that in relation to your personal equity and financing situation?

Any other pitfalls come to mind?

Why should there be any? You are building a house according to standards that the legislator rewards with subsidies; they are owed to you.

The only difference is that you are one of the few who would be able to repay the money from the associated loan directly. Whether it’s worth it or if you’d rather let the loan run normally like most others, you have to calculate carefully.

Is that an amount that isn’t really worth it, or am I miscalculating somewhere?

He is speaking from the perspective of the intermediary bank. They earn almost nothing from the KFW funds and therefore usually have no interest in issuing them "solo".