Home purchase financing despite high interest rates?

The biggest problem with the building savings contract is not the closing fee, it is the negative interest rate spread business. You save money at 0.1% while paying x% for the loan. Whether as interim financing or as a reduced savings rate. The Z15 is actually a special case here, since the repayment is not freely selectable, no special repayments are offered, and the Z15 itself is a very attractive loan if you qualify for it (and do not have to wait 2 years for the money). There is actually a chance here to come out better overall with the building savings contract than with alternative investments. The whole thing depends on the interest rate level for overnight money/fixed deposits during the savings phase and the interest rate level of the follow-up financing. So it is difficult to predict.