Is financing the construction of a house feasible?

Basically, you are right. I interpreted it a bit differently: Single-family house with 150m² approx. €500,000 DPH with 2x150 m² approx. €850,000 The calculation is of course more complex. Possibly double KFW funding. Rental income. Consider tax/depreciation.

You really have to calculate carefully. If you have an income tax rate of 42%, the new depreciation can already be very attractive. Especially if the QNG bonus is still possible.

All in all, we are looking at a total sum of €500,000 here

Loan: €400k
Installment: €1900/m (Minimum 2% repayment over 20 years)
The bank calculated "living costs" for us in 2019: €2300/m
Inflation: 19.3%
Living costs (2024): €2700/m
Land: €800/m
Total €5400/m

There is already a shortfall of €500/m (from the perspective of banks and reasonable people).

Still, good luck.
Maybe it will work out.

Regards

2700€ living expenses for a couple?

One could consider reducing the repayment to 1.25% at the beginning and increasing it after three years when the [Grundstück] is paid off.

2700€ living expenses for a couple?

Yes, for a couple with two cars

2700€ Lebenshaltungskosten für ein Paar?

Flat rates are always calculated based on ranges of the total net income including child benefits etc. For a couple, this can be between €1,400 and I believe just under €4,000 with us (I’m on vacation and don’t have the current tables in mind).

2700€ are depending on the region either a palace with 3 cars or 60sqm and bike + Germany ticket only. 1500€ rent, 500€ food/hygiene and then you only have "just" 700€ left for car, vacation, and unplanned purchases. Carbonara style is less, but as a guideline plausible.

if you are allowed to post this I would be very interested, I actually found the values rather low. It was a few days ago, but I think we were even granted slightly over 50% of the net fixed, which would be totally crazy. You can gladly spend that on the special repayment, but having to pay that fixed is madness.