Which financing option, TH or building savings contract?

I also tend to prefer V1, as I am flexible with the [Sondertilgung].

Well then. With the building savings contract, as soon as you are in the loan phase, you can repay unlimitedly.

I would sit down and calculate what is realistic for extra repayments and go through all variants *completely*

Otherwise, prepayments are very often overestimated. Only 1-2 out of 10 actually use them regularly.

I am actually disciplined in that regard

If that is the case.

So, if you make a €3,650 special repayment every year in option 1 (to compare it better with option 3), the follow-up interest rate can rise up to 5.9% before option 3 becomes worthwhile.

However, if you do not make any special repayments for whatever reason, then option 2 (the safest one) is already better at a follow-up interest rate of 3.2%.

Scenarios in between can certainly be calculated as well; but for that, I need more than just pen and paper.

By the way, option 2 is not worth it at all if you actually make regular special repayments in the range of 3650. (Or if you put it into the [Bausparvertrag] for the first 15 years and then also make special repayments again.

Option 1 only becomes worse if the follow-up interest rate is 6.9%.

You have the choice

But since you plan to make even higher special repayments, option 1 is clearly the favorite among the 3 proposed options.

@For the [Bausparvertrag] skeptics. If the original poster didn't make so many special repayments, option 2 would clearly be the best concept of the 3 presented. With a marginal rate of 3.2%, you really must have drunk heavily from the optimism bottle to think interest rates will be the same again/still in 15 years