Addendum: How can I plan my financing even though the KfW interest rates are not yet known as of April 1, 2016.
Certainly without any legal binding and partly based on our specific case.
Background: We had already spoken with our house bank in September about a possible financing, agreeing on framework, rate, and options. In the conversation, it was also hinted that it might be possible in terms of timing to already plan with the new KfW conditions.
If the land purchase and building application are completed by the end of 2015, we will deal with the financing at the beginning of 2016. In this case, the whole thing would be set up and planned fictitiously, for example for the 20-year fixed rate loan at 1.25% interest. Based on this, interest and installments would be calculated. Once the actual conditions are announced, the financing would be adjusted accordingly. For the 20-year fixed rate, 0.5% above the current 10-year rate. Certainly, one can also plan in a bit more buffer here, but my forecast was also in that region.