Bullet loans & annuity loans combined - sensible?

Did you account for the full special repayment each year in your calculations? How else do you come up with a sporty 9.x years?

As just mentioned, we are currently calculating with €7,000 special repayments per year on the annuity loan and are therefore repaying within 9 years and 5 months and thus within the fixed interest period. I can't really make special repayments on the home savings contracts, which is why we included that component.

The information is incomplete to validate whether the 350K€ are really paid off and the total costs are correct. But if both are the case, that looks very attractive in my opinion. Alternatives 1) Full repayment loan 20 years at HVB with 1.0%, but the rate is then 1600€. 2) Annuity loan 15 years at 0.9% e.g. HVB or Degussa, with a 1400€ rate about 130K€ remaining debt. That is manageable.

At the beginning we can/want to repay even more. Currently, 2000€ is planned. So maybe an annuity loan with an adjustable repayment rate would be possible? With a full repayment loan, I have to pay the same fixed amount for 20 years and cannot adjust it, right?

What is the best way to get an offer from HVB or Degussa with as little commission/fees as possible?

Correct, many banks include an option to change the repayment rate for free. Either x times during the term or once a year. The adjustment can usually be made between 2 and 5%.

If you go to a building society, you get a building savings contract... You simply have to find the right provider for your needs. Obviously, you were recommended the wrong one for your requirements. There are brokers like sand on the sea. Either the well-known large ones or, for example, use the comparison calculator on Focus online and then choose a provider yourself. For example, we have had very good experiences with DKB Grund, they also broker all other banks.

Regarding your special repayment. Just try using a mortgage calculator.

I have calculated:
350K loan, fixed for 15 years at 1.00%
Installment €1400
Special repayment of €7K each in the first 8 years

results in:
Remaining debt after 15 years €72.7K
Full repayment after 19 years, 4 months
Interest over the entire term €30.7K (with a constant interest rate in the last 4 years)

For example, on baufi24 you can play around with your data however you like. How about 200€ more installment for that without (fest geplante) ST?

For example, on baufi24 you can play around with your data as you like. How about 200€ more installment without (fixed planned) extra repayment?

Since we are taking out the loan together and only one of us will make the extra repayment, that wouldn't be such a good solution, or it would make things more complicated.