How much income do we need for our home loan?

I wanted to give a little update. The construction companies we have spoken to so far estimate the effort at a total of 360,000 to 550,000 including outdoor facilities, basement, garage, air-water heat pump with underfloor heating but without the extension. We will probably leave out the extension as well. We found a better solution and will instead build out 2 more rooms in the basement.

Of course, we have the 5000 for a new car as a reserve. I did not count that as equity. We wanted to leave about 8k for everything that comes up unexpectedly.. car breaks down, washing machine breaks down, etc.

You can't really narrow down the house construction so precisely when taking out a loan that you can plan with 8k left over. Plan so that, for example, 40k€ remain after the build, that is your buffer for everything. Whatever is really left over after that, put it into special repayment or leave it as a buffer for daily expenses in the account.

It might also make sense to declare all equity to the bank and simultaneously increase the loan in order to improve the equity ratio.

It may also make sense to declare all equity to the bank and at the same time increase the loan in order to raise the equity ratio

since equity actually always has to be spent first before the first credit ruble rolls, the OP is then left completely naked. Unless there is some of the loan left at the end that the bank transfers blank.

Indicate all equity, contributing only a part can help.

Apart from the fact that your salary situation is very comfortable, 200 sqm is really a huge house for just 2 people. Keep in mind that it also needs to be heated, maintained, and cleaned. I think for 2 people 150 sqm is already a lot. Take a look at houses that have 200 sqm. You will be really lost there. Unless you are planning a swimming pool and a gym in the basement. And I would doubt that you have less stress with prefabricated houses than with masonry ones. For us, everything went perfectly with masonry; our neighbor with his prefabricated house had significantly more problems and in the end was also considerably more expensive with the same equipment.

Aside from the fact that your salary situation is very comfortable, 200 sqm is really a huge house for only 2 people. Keep in mind that it also has to be heated and maintained, cleaned. I think for 2 people 150 sqm is already a lot. Look at houses that have 200 sqm. You are practically lost there. Unless you plan to have a swimming pool and a fitness room in the basement. And I would doubt that you have less stress with prefabricated houses than with masonry. For us, masonry went perfectly fine, our neighbor with his prefab house had significantly more problems and in the end was also significantly more expensive with the same equipment.

Actually, the house is supposed to include a sports room, plus 2 offices, since we both mostly work from home and therefore need proper offices. Then it’s not so much anymore. It’s not even about 200 sqm, but maybe 170 or so.

Every room is already firmly planned. 1 office plus bedroom, plus small laundry room, sports room, plus bathroom upstairs. Downstairs living-dining room, kitchen, bathroom, guest room, pantry and in the basement an office, hobby room, pet room (currently the guest room and pet room are one room due to lack of space and that is so annoying. My animals have their retreat there, sleep there, have their toys, litter boxes etc. there. Rearranging every time guests come is very time-consuming).