That is very well calculated. In my opinion, your wife's fixed-term employment is not a problem because the income does not make up a significant portion, and lifelong unemployment is not to be expected. An open-ended contract can also be terminated within the statutory notice periods if necessary. In case of doubt, you could reduce the 450€ net ?! for retirement provision. You also have a company pension and then an additional private 450€, right, or is half a direct insurance, which means it is not available net in case of doubt? Once the house is built, the incidental costs could be adjusted a bit upward. I don’t mean just the fixed incidental costs, but also costs for lawnmower, repair work, various accessories or connections, repairs, garden items, light bulbs, things for the children's rooms, curtains and such things, etc... So with a similar initial situation as you, it is actually about 300€ more per month than we originally assumed. The savings amount for new cars should also be considered; I mean 200€ per month is quite low for maintenance of the current car and saving for a new car. Electricity 45€ is also very sporty, we have a volume tariff that fits exactly and yet we come a bit over 45€ for 180 sqm. There is simply more running in the background in a house than in an apartment. What is included in your 300€ incidental costs? Because if insurances are not included, then 50€ per month is a bit low for term life insurance, accident insurance, disability insurance, house + elemental and other small insurances, which together often amount to 200€ per month. If children and wife have the same insurances, then even more again.