Kfw 55 for 2We, which variants are sensible?

Hello
I am planning to build a two-family house with 280 sqm of living space with my parents. Land available Total planned construction sum 500k€.
My parents can pay their part and do not need a loan. I have saved about 100k € and would take out 2 Kfw loans, i.e. 300k €. My net income is 2100€ per month. Does it make sense to take out one loan for 10 years (0.64%) and one for 30 years (0.81%) or both loans for 30 years and then see what can be repaid after 10 years?
Regards barek

That doesn't make any sense at all. 280sqm for 500TEUR? Financing 300k with 2100 net income is, depending on your life situation, something I would also call very ambitious. KFW 55 expires on 31.01., so you can forget about that anyway. Sorry, but that stinks.

Just fill out the ENTIRE questionnaire first, maybe some contradictions will then be resolved. However, the budget can only be described as wishful thinking.

Total planned construction sum 500k€.

Only for your 140sqm is ok including incidental construction costs and earthworks.

Take out 2 KfW loans, so 300k €.

Does the bank already know that? Many already have a stop on acceptance, in seven working days your financing would have to be completely approved AND also with the KfW including the documents from the energy consultant.

I plan to build a 2-family house with 280sqm living space together with my parents.

Ownership relationships clarified?

I have a net income of 2100€ monthly. Does it make sense to set one loan for 10 years (0.64%) and one for 30 years (0.81%) or both loans for 30 years?

With 2,100€ net it makes no sense at all if you become the sole borrower. Your household calculation simply doesn't work.

The most important thing is the ownership status. You will not get a loan for what [die nicht gehört].