Financing plan - sounds almost too good for us

The annual premiums are 100 percent secure. The drawback of the repayment change is of course really present. If I do not repay anything in the first 13 years, I cannot adjust anything except the savings rate for the [Bausparvertrag].

I have now calculated based on your information. Only referring to interest, you pay about EUR 1,500 more over the entire term with the building savings contract option plus the closing fee for the building savings contracts. I assumed a reasonable interest rate of 3.50% (which should actually be significantly lower if you look beyond your immediate perspective). This is a constant rate of EUR 1,150 per month.
In addition, with most banks, you have the flexibility to adjust the repayment rate (what about your family planning, for example?) or to make special repayments. After 10 years, you also have a special right of termination.
P.S. If the building saver has saved TEUR 45 and you make a special repayment of TEUR 13, only TEUR 32 and not TEUR 42 need to be financed. There is a calculation error somewhere here.

The problem is that local banks in Saxony hardly offer 20 years at all, and if they do, then at 4% and more. That is no alternative here.

It was the same with us. But as soon as a financing professional requested from the same bank, 20 years and 3% suddenly were no problem anymore. We have therefore left our house bank in the meantime. We were told several times at the table that it was absolutely not possible and that you are better off with a building savings contract. We have financed €200,000 at 3.1% fixed for 20 years, and that was a year ago. Now the interest rates have dropped again. However, in our case, it is only a 60% financing. That also makes a difference.

If the closing costs etc. are already included in the [Bausparvertrag], the offer seems quite good... Corresponds to an annuity loan of about 3% over 20 years.

I myself currently have an offer for 20 years as a full repayment loan at 2.83%.

The advantage of the annuity loan is, in my opinion, the simplicity compared to the [Bausparvertrag] situation and the possibility to make special repayments...

@shism I recalculated, the offer corresponds more to an annuity loan of about 3.50% for 20 years (taking into account the closing costs of the [Bausparvertrag] even more). The big catch is that for 13 years !!! not a single euro is repaid. With an annuity loan with about 3.5% repayment (= full repayment), half of the loan would already be repaid at this point and the interest burden significantly reduced. In my opinion, the offer is bad and inflexible. I could not recommend it to my clients (unless I am concerned about my commission statement at the end of the month)...

so I come to a monthly rate of 1067 in the [Bausparvertrag] phase and 1133 in the savings phase... = 1110€/month on average over 20 years If I compare that with a full repayment loan over 20 years, it would have to have an interest rate of ~3%... at 3.5% I would rather end up at 1160€ that I would have to pay monthly... Or how do you get to 3.5%?