Prepayment penalty and repayment rate change - experiences

Hello everyone,

we are currently thinking about what to do with our condominium once the single-family house is completed. Originally, we actually thought about renting it out, since both properties are only about 30 minutes apart and therefore it is not a case of renting "from a distance." However, since landlords in Berlin are generally labeled as greedy and almost equated with organized crime, our current tendency is to sell the apartment. (excluding the rent cap, of course)

Now we come to the topic of prepayment penalties. These will be relatively high, as the decision to build the house came faster than expected. Questions:

[*]Does anyone have concrete experience with how accurate the calculations of the various online calculators are? In other words, can you more or less rely on them? I recently used the one from Interhyp.
[*]According to the loan agreement, I have two opportunities to change the repayment rate within a corridor between 2% and 6%. It is not entirely clear to me whether this is automatically taken into account in the bank’s calculation or if it makes sense to increase the repayment rate to 6% shortly before terminating the loan, since that would naturally reduce the interest loss. This is not mentioned in the loan agreement; I had read online that it should actually be considered.

PS: I am aware of the ruling concerning the Commerzbank, where the prepayment penalty was deemed unlawful due to unclear calculation. Depending on how things develop, I might pursue this route, but I cannot assume this at the current time (Commerzbank is not the lender).

I hope there are some experiences here. Many thanks!

Does anyone have concrete experience with how exactly the calculations of the various calculators on the internet are? In other words, can you more or less rely on them? I recently used the one from Interhyp.

They fit relatively well.

According to the loan agreement, I have the option to change the repayment rate twice within a corridor between 2% and 6%. I'm not quite sure whether this is automatically taken into account by the banks in the calculation or whether it makes sense to increase the repayment rate to 6% shortly before terminating the loan, since of course this results in less interest damage. This is not mentioned in the loan agreement; I had read on the internet that it actually "should" be taken into account.

It should indeed be. But you can recognize this from the calculation (possibly have it checked by consumer protection organizations) and react accordingly.

Interim loan and collateral exchange would not be an option?

Would a bridge loan and collateral swap not be an option?

For the loan amount of the new property, I want the longest possible fixed interest period (20, preferably 30 years) to minimize the residual debt risk. With the current bank, a maximum of 15 years is possible and the conditions are currently not particularly good. I have already spoken to the current bank about this, but no real solutions were offered. In addition, we now want to fix the financing terms for the new property and not only in at least 12 months (rather longer) when we would repay the bridge loan. The reason I am asking the question now is that if I sell the condominium, I would still use the special repayment this year. It would not have made sense to do so with the subsequent rental.