Building a single-family house with a basement - Is the financing calculation too risky?

Hello everyone,
I am new here and would like to get your collective knowledge or an assessment:

Next year we are building a detached house with a basement in solid construction. The cost for the house alone will be about 700,000 euros (+ kitchen and outdoor facilities) and we already own the land. We will need to finance 500,000 euros and do not intend to pay it off in more than 20 years. We want to pay a monthly installment of 1,500 euros cold + 500 euros additional costs, if that is feasible. My husband and I both receive bonuses at the end of the year and therefore want to make special repayments of 15,000 euros annually from that. Our net income is 6,000 euros per month. We both have company cars. Children 2. Kindergarten costs 400 euros per month. However, we have high monthly fixed costs due to insurance and savings contracts and of course a high standard of living, so we spend 3,000 euros monthly on that. Is it then unrealistic to plan this way? Thanks for your help

What are your plans for the outdoor area? From personal experience... when you build such an expensive house, you also have different demands for the outdoor area and kitchen. You should have the funds for that. Kitchen with us: 50k, outdoor area 250k... the amounts quickly add up, unless you have a small plot and corresponding taste

Why does the house have to be so expensive? 6000 net is too little for your plans.

Outdoor facilities 100,000 euros, kitchen 50,000 euros, the 6,000 euros are just our base salary, without Christmas bonus and holiday pay (we left those out as special expenses – that would be another 7,000 euros net) as mentioned we both receive a lot of bonuses and premiums (if I calculate that over 12 months, we come to a total of 9,000 euros net), the money for the outdoor facilities and kitchen is available.

Unfortunately, the house is expensive because we will be building on a fairly steep slope, which of course is great in terms of location, but for that reason, the basement alone costs 110,000 euros. The total is 200 sqm + basement

With a maximum of 1,500 euros per month and 15,000 euros in special repayments per year, you would have 660,000 euros over 20 years that you can/want to repay at most. An intermediary or bank advisor can probably best assess whether they can offer a loan with a corresponding interest rate. I am not a financial expert, but theoretically, especially in the current interest rate situation, it should be feasible.

However, if 3,000 euros of 6,000 euros net every month go solely towards the cost of living and a large part of the bonuses is then paid as special repayments, the room for savings measures would already be somewhat tight for me. Then a certain large portion of the 3,000 euros should flow into your savings contracts/retirement provisions, and there should also be sufficient equity for outdoor facilities or kitchens.