Follow-up Financing 2030 Prepare Now Building Savings Contract/Special Repayment/Fixed Deposit

I have to be honest that I simply can’t come up with a good idea for the next 7.5 years. Only risk brings returns and that is quite a lot of risk over this period.

Risk-free in the end is simply fixed deposit or special repayment... Fixed deposit gives you 100% more and special repayment reduces the monthly interest... With my 759 + 350 currently, that is 1.10 euros less interest every month. That means that in just under 7.5 years towards the end, I will pay off almost 100 euros more every month than the interest I pay...
I think that sounds like a reasonable solution... At least then I have something immediately... And I could even increase it to 759 + 350 + 250.

Unfortunately, I have not found a suitable calculator on the internet or as an Excel solution that reflects my view.

Loan now 206K: 759 rate without special repayment 30.06.30 = 156K
Loan now 206K: 759 rate with 350 special repayment 30.06.30 = 122K
Loan now 206K: 759 rate with 550 special repayment 30.06.30 = 102K

I can understand that with people who still owe 300,000 EUR+ on the follow-up financing and pay a rate of 1,800 EUR. But with a rate of just under 800 EUR and 150 tEUR? In 7 years? There is virtually no risk that one won’t be able to manage this, even if the interest rates stay the same, right?

It's not about feasibility... I just don't want to end up paying a rate of 1000 euros where the repayment is the same as now and the rest is interest that shoots up. That's why the [Bausparer] is always on my mind. Assuming we go to 6-7 percent... Then I'll just laugh in the end if I only have 2.35%. If the market interest rate is at 2, then I don't need to take the [Bausparer] and have only incurred a slight loss because I wasn't aiming for a risky return... But either way, I then have a low interest rate and repay more. I somehow like the construct, but I feel like maybe I'm missing a component. I can't describe it and above all can't calculate it...

It doesn't matter how you turn it. Now you are paying the extra repayment with partially devalued money due to high inflation. And in 7.5 years, you might have higher interest rates (which is by no means certain), but the remaining amount has also been partially devalued by inflation. Wages will have to rise, although not as much as inflation. And it has already been said elsewhere. What you pay into the [Bausparer] or extra repayment, that is gone. I find it almost funny that something like this can ultimately lead to people not being able to pay their installments anymore because they have put all their reserves into the extra repayment and unexpectedly go into short-time work or are even laid off. But the bank wants the installment, not the extra repayment ;)

You get 100% more with fixed-term deposit and prepayment reduces the monthly interest...

I think there is a flaw in the reasoning. As long as you receive the same interest after taxes on your investment as you pay on the loan, it does not matter whether you repay now and save interest or invest money and repay later. And with double the interest rate for fixed-term deposits, the matter is actually clear. I would rather look more at the psychological aspect. What is repaid is gone and cannot be squandered anymore. As long as you plan sensibly, have an appropriate emergency fund, and are in a suitable profession, you don’t have to immediately assume the worst case.