Is a single-family house in the Stuttgart metropolitan area still affordable?

Even without the granny flat, I find the project way too tight. The property simply costs a lot of money, but there is no equity available. This results in a loan of €800,000 or more. There is no equity buffer for unforeseen expenses. I view parental leave with multiple planned children very critically.

The exciting question is: How much is the apartment worth, and what is the remaining debt + prepayment penalty?

I cannot imagine that such a project is feasible without selling the apartment.

The crux of the whole story is the question of wanting children. If you remain DINKs, it is doable, although I myself would give up the apartment as well as the granny flat. If children are planned, it is a surefire recipe for big drama; one can only hope that no one gets the idea to finance it.

You are right, as DINKS of course everything is no problem but with each child the finances get tighter and tighter.

With my proposal, the rate would be 2600 euros plus additional costs. Let's say 3000 euros.

It's also a question of how the "6600€ monthly" is currently divided. One 4000, the other 2600? If one is in tax class 3, it would be 4600 euros net. That means there would be about 1000 euros missing during the parental allowance period of 1700 euros. Times 12 months.

With 3100 each, we're talking about 3600 for the one with tax class 3 and 1800 euros parental allowance, so 5400 euros or a 1200 deficit. Times 12 months.

Something like that has to be bridged with every(!) child. So should still be available as backup in case of tight cash flow. After that, however, everyone must work full time again. Daycare costs in S are about 200 euros as far as I know, so that already adds up mathematically with the child benefit. Whether you can manage without part-time (grandparents nearby?) you have to decide. You will also tend to end up with one or two children instead of two or three (based on experience). Is it worth it to you or how should the planning go – that's for you to decide.

Possibly you can also stretch the repayment period to 30 years and thus accept 300 to 400 euros less installment. Bonuses and salary increases should then be consistently used for special repayments.

So my cousin and her husband bought a house worth a total of 1 million three years ago with a net income of 6k. They were about the same age as you then. However, their equity was somewhat higher at 200k. None of the banks they approached had a problem financing 800k. They pay 3000 per month, and with that, the loan will even be paid off as planned in 25 years instead of the existing 35 years until retirement. Currently, my cousin is on parental leave, but that’s not a problem for them. Their family income is only 5300, but that’s enough for them. However, I’ve already learned here that this must be evaluated very subjectively. Some people can still save a lot with 2300€ without rent, and others can’t make ends meet with that. Of course, one would have to decide that beforehand before plunging into ruin. Normally, banks don’t really care about upcoming family planning in a caring way... By the way, my cousin doesn’t plan to work full-time, so that’s possible too.

What would personally bother me terribly, however, is that neither of them can be disabled or unemployed for a long time. Likewise, it would bother me a lot that I wouldn’t have the option to freely decide to maybe stay at home with the child for 2 or 3 years on parental leave. It’s also a difference whether you voluntarily get by with little money or whether you really CAN only spend little money for a long time.

So overall, I would also advise you to skip the granny flat and reduce the scope accordingly. But I fear there isn’t really much room to go lower. Our plot was similarly expensive to yours, and 1 million will not be enough for us with all ancillary costs and outdoor facilities... And if I were you, I wouldn’t be able to sleep peacefully anymore because you don’t know during construction if the cost won’t be 100k higher again :-(

They pay 3000 per month, and with that, it will even be paid off as planned in 25 years instead of the existing 35 years until retirement.
Currently, my cousin is on parental leave, but there's no problem for them. Family income is only 5300, but that's enough for them.

In this case, after additional costs, ~1,700€ remains for living for a small family. That is probably close to the poverty line in cities like Munich or Stuttgart. But then wanting/having to live in a house worth 1 million. The poor children...

In this case, after additional costs, about €1,700 remain to live on for a small family. That is probably close to the poverty line in cities like Munich or Stuttgart. But then wanting/having to live in a house worth 1 million. Poor kids...

That wouldn’t be for us either. If the child asks, "Why don’t we travel," then answering, "You have the house, why do you want to travel?" is like buying a Ferrari and then putting winter tires on steel rims because there isn’t enough for alloy wheels.