Is the construction project feasible?

Attention: Employer loans must not be interest-free, otherwise they constitute a taxable monetary benefit!

In the long term, my income will gradually increase from the current 3450 gross to 4500 gross over 18 years.

In about 10 years, I will inherit a renovated and energy-efficient pension with 4 holiday apartments and several single rooms and apartments.

I am always amazed at how well some people can plan their lives! Great! Does the testator also know the schedule? :p

By the way, I believe that it is not necessary to spread all personal details (of course, one may do so and no one forces me to read). It would be sufficient each time to provide the key data. It also helps the person asking the question a lot, in my opinion, if they put together these key data. Then things become clear and many questions become unnecessary.

Many expectations are priced into all your figures and it somehow seems detailed ... The tip about the household book has already been mentioned here. Sit down and distill a figure in euros/month that you can reliably spend on housing. From that, ancillary costs would have to be deducted and the rest is available for repayment and interest. Then you know more.

By the way, the property is already worth a lot and more than many other home builders can show.

Regarding the loss carryforward: Are you sure you can get together 25,000 (or 20,000?) there? It’s one thing what you calculate for yourself, but of course a completely different matter what the tax office later recognizes. And even if at best 25,000 goes through, that amounts to just over 4,000 euros at your current tax rate of about 17%. I would consider anyway whether the Bafög loan really has to be paid off immediately – after all, it is interest-free. It only really makes sense if you could get a significant discount through immediate repayment, and even that should be weighed against the repayment period and you should consider whether the money would be better invested elsewhere with a higher yield (e.g. with the construction loan ;-) ).

As for the estimated costs, I also lack experience. But let’s assume your estimate is correct and you get the whole thing for 220k, which you would then have to borrow. Currently, as far as I can read, you get 100k credit per approx. 450 euros monthly installment, which would mean you would have to manage a monthly rate of 990 euros. Let’s further assume that you do not have children and calculate with both incomes (without “special items” like vacation and Christmas bonuses, bonuses, expenses etc. (those are simply not guaranteed)):

2150 + 1100 = 3250
According to your statement, you currently have 1300 euros left over, from which let’s say exactly 310 euros goes towards additional costs (which you apparently currently do not pay, if I understand you correctly). That leaves you exactly the mentioned installment.

But what happens if you do have children, who will take care of them (or who will be paid for childcare)? What if the house ends up being more expensive? What about insurance? What about vacation, “luxury” or expensive purchases in between (washing machine breaks down, car doesn’t last forever, lawnmower etc.)?

That would be too tight a calculation for me. Then try renting an apartment instead, wait a few more years and save – at 21 your girlfriend is still very young for such a project anyway. I don’t really understand the requirement “office AND children’s room” (so at least 4 rooms?!) anyway. At the moment it even seems to work with “neither.”