We have an integrated building savings contract. The explanation is not as complicated as initially presented.
You take out a loan with a short term (in our case 10 years) and enjoy the low interest rates. But since you don’t want a rude awakening after 10 years, you take out a building savings contract that you save into in parallel. This will become eligible for allocation after 10 years with the associated loan and interest. Then, in 10 years, you can decide whether you want to arrange the follow-up financing through the building savings contract or if the interest rate level is still low enough that a classic loan pays off again.
Using our example:
Loan amount 400,000 (50k equity)
100,000 € Kfw with special repayment, due in 10 years, outstanding debt about 80k
150,000 € classic loan with 10-year term, interest-only repayment
150,000 € classic loan with 10-year term, interest-only repayment
50,000 € building savings contract already eligible for allocation, will replace a loan in 10 years
50,000 € building savings contract, being saved into and will be eligible for allocation in 10 years, replaces the other loan
Outstanding debts that are not secured will then be about 80k.
But you pay for the security. One should be aware of that.