Special repayments or investing in the market? Alternatives?

I would split it. Pay 5% in special repayments and invest the rest in the stock market. But it also depends on how high your remaining debt is. The higher the remaining debt and the lower the fixed interest period, the riskier it becomes. Then I would pay more special repayments. Ultimately, it always depends on your own risk tolerance. Personally, I don't feel comfortable with high debts, even though I rationally know that probably fewer special repayments and more ETFs would be more profitable. But that's just probably...

We can definitely live well with the remaining debt after (now still 17 years of fixed interest). That is not the problem. We have also consciously chosen a moderate rate.

Well, you have to pay almost 30% tax on the returns from the stock market, or did I misunderstand that? In the end, 1% makes a difference with the interest burden.

25%. Then 6% return before taxes becomes 4.5% after taxes. Still twice as high as your loan interest rate.

I would split it. 5% for special repayment and the rest invested in the stock market.

5% of the money left at the end of the year? Hardly worth it, especially since the bank doesn't always accept small amounts. I mean, I have to deposit at least €1000, so that would be an annual surplus of €20,000.... hardly anyone has that much left over.

25%. Then 6% return before taxes becomes 4.5% after taxes in the end. Still twice as high as your loan interest rate. 5% of the money left at the end of the year? Hardly worth it, especially since the bank doesn't always accept small amounts. I mean, I have to deposit at least €1000, so that would be an annual surplus of €20,000.... few have that much left over.

With church tax and solidarity surcharge, it's nearly 30% as I just read. Or I have a wrong source... We've paid 5% of the total original loan amount as special repayments each year so far (there have only been 3 years). Now we have a child and naturally less money available. But we also received a bit from my parents. Therefore, we have too much money in our accounts and wonder – where is the best place to put it? With 1.x inflation, it wasn't so important to me before, but now I have that back on my radar.

with church tax and solidarity surcharge it's nearly 30%, I just read. Or I have a wrong source...

Mea Culpa, with the solidarity surcharge it is 26.375%. I don't count church tax, just like football club or other private pleasures ;)

5% of the money left at the end of the year? It's hardly worth it, especially since the bank doesn't always accept small amounts. I mean, I have to deposit at least €1000, so that would be an annual surplus of €20,000.... very few have that much left.

That’s of course true again, that you can’t generalize that. We have cautiously chosen the rate for our current consumption habits and planned for the worst case that my wife’s civil servant appointment doesn’t work out as expected and also so that the rate would still be manageable with parental allowance.

Furthermore, the KfW portion of the loan amount, on which the 5% refer, is deducted, where there is no special repayment right.

Like the original poster, our parents also supported us more during the house construction than originally planned and paid some bills.

That’s why it would initially be easy for us to repay 5% early. Once the kids are here, it will get tighter for us. For this reason, it might also be a sensible consideration for us to have a larger reserve in the overnight money account. This could then be used in an emergency for the first years with children.

However, you can see, it is very individual and a lot has to be taken into account.

Exciting thread... I have already thought this through in my head as well. However, I wonder whether one should also consider the appreciation rate of the property; the faster I pay it off, the more I also benefit from the property's appreciation (or am I mistaken), because then a larger share already belongs to me and, in the event of a sale, relatively more comes back to me. Unlike the stock market, real estate is not so volatile. But I think I would also try to make a mix, whereby I see investing in ETFs more as a universal savings option, i.e., an investment that one could also use for investments or as a reserve, although perhaps a [Tagesgeld] account is better there. I am not an expert, but what you often read is that the ETF savings plan is the new savings book with the advantage that, in the best case, you can achieve quite good returns, but in the worst case also suffer heavy losses, provided you need the money at the wrong time.