The first step has been taken today

3.4% but the remaining debt would have been too risky for me personally.

I just calculated an example. I simply assumed €200,000 and, since you didn’t want any remaining credit, I assumed full repayment within 30 years.

Loan €200,000
Interest rate 3.6%
Fixed interest period 30 years
Monthly payment €909
Remaining balance after 20 years €91,621.33
Remaining balance after 30 years €0

Alternatively
Loan €200,000
Interest rate 3.4%
Monthly payment €909
Remaining balance after 20 years €82,724.86
After that, the interest rate will be reset.
At approximately 5.75% interest, it is the break-even point.
That means at a future interest rate of 5.75%
= Remaining balance after 30 years is also €0

Anything above the expected interest rate of 5.75% would of course argue in favor of the 30-year fixed interest period.

Since you apparently also want special repayments, I have also calculated a few examples for this.
With an annual special repayment of €600, the break-even is at an expected interest rate of 7.1% after 20 years. (Term approx. 27.5 years)
With an annual special repayment of €1200, the break-even is at an expected interest rate of 9.5% after 20 years. (Term approx. 25 years)
With an annual special repayment of €1800, the break-even is at an expected interest rate of 16.0% after 20 years. (Term approx. 23.5 years)
Assuming a constant monthly payment.

So anyone who regularly plans additional special repayments should not choose too long a fixed interest period.

clearly explained :)

I would like to point out a few things regarding interest rates:

if the interest rate rises above 3.6% in the first few years, making special repayments on the loan would be wrong. The money should then be better invested at the higher interest rate (actually logical but sometimes one is just blind to it) and no one can really count on possible special repayments otherwise they could have just accepted higher installments right away.

and secondly:

look at the interest rate development over the past 20 years. Back then we were between 7.5 and 9%..... anyone who claims that this can never happen again might be making a big mistake.

If the interest rate rises above 3.6% in the first few years, special repayments on the loan would be wrong. The money should then be invested at the higher interest rate (actually logical but sometimes you are just blind to the operational situation)

I don’t understand that. If I have a fixed interest rate for 20 years, it doesn’t matter at all how the interest rate develops.
If you think I should invest my money at 3.6%, you’d have to show me a bank that is secure enough and actually does that :) All these banks advertising 4% overnight money accounts are anything but reputable. Every special repayment makes sense, because it shifts the annual payments in favor of the principal repayment.

and no one can really count on guaranteed special repayments; otherwise, you could have just accepted higher installments right away.

From that you see that it is completely individual how people plan their financing. Our financing plan is based almost exclusively on special repayments. We have kept the monthly rate as low as possible in order to have as much flexibility as possible. We plan fixed 5-10% special repayment every year.

High interest rates at the end are quite possible. But what you don’t want to understand is that if you still have a remaining debt under 30,000 at 9% interest, that hurts less than having paid too much interest for 20 years.

All these banks advertising 4% overnight money accounts are anything but reputable. Every special repayment makes sense because it shifts the annual payments in favor of the repayment portion.

and again you assume the current interest rate situation. What will you do if in 10 years you get 5% for overnight money? Special repayments?

That high interest rates at the end are quite possible. But what you don’t want to understand is that if you still have an outstanding balance under 30,000 at 9% interest, it hurts less than having paid too much interest for 20 years.

If you have an outstanding balance of 30,000, then it’s no problem at all, but many loans are so bad that the outstanding balance after 10 years is so high that the interest can no longer even be paid, and that happens (can happen) if you agree to terms that are too short.

Of course, everyone has to decide that for themselves, but the risk is often overlooked.