Update 2:
Nothing new from ING yet. It will probably remain on November 3rd.
There was a conversation with Sparkasse Brandenburg. It was very, very pleasant. Thanks a lot to you for this tip, regardless of how it turns out.
First, many questions were asked about us and the house. I found that good because you could tell that someone was trying to get a clear picture. The advisor was not surprised about the construction sum, although she also said that with that amount we belong to the more expensive houses in the region. It came up during the conversation that from her perspective there are no problems, neither regarding creditworthiness, nor the term or the property value, where she reached over 600 k. Since we are below that with the loan amount (I had also slightly reduced the loan amount by 20 k), it would fit very well. In addition, they only need 2-3 days for the review/approval and are generally very relaxed with the payout.
The only "disadvantage": they finance for a maximum of 15 years. For 0.88%. In general, I can imagine that, because the remaining debt due to interest, lower loan volume and thus higher repayment is lower than with ING after 20 years and would be around 225-240 k, depending on whether the KfW loan is fully repaid after 10 years.
She will call me on Monday. Now the question is what we do: either way, this offer seems better than ING's (560 k, 20 years, 1.28%, remaining debt 280-300 k). The loan application is still running there. And since we had already started the process with ERGO, with known results, I don’t want to harm our chances now. There should already be two entries in Schufa (ERGO, ING), which will negatively affect our score with further loan inquiries. Additionally, I am cautious whether we would eventually get the loan from Sparkasse as well, although the word from the Sparkasse advisor is probably more reliable than from a loan broker.
Before I give her a commitment, I would at least have to wait for ING, or are two parallel loan inquiries unproblematic?
Next Tuesday, I also have a conversation with Sparkasse Berlin.