Your opinion requested / unmarried financing

No problem. Buy the property and properly register yourself in the land register. You can also make the contractual arrangement with your girlfriend later (but please make sure to actually do it). It's not like a new house will be built on the day of purchase... and then you break up immediately. Why is marriage unthinkable? Is the remaining financing already secured? Is your income sufficient to manage it?

No problem. Buy the property and make sure to register yourself correctly in the land register. You can arrange the contractual agreement with your girlfriend later (but please do it for real). It's not like a new house will be standing there on the day of purchase... and then you both break up immediately. Why is marriage unthinkable? Is the remaining financing already secured? Is your income sufficient to manage that?

I will definitely do that. Our plan was:

To contractually regulate things like this: 1) Who stays in the house after a breakup? Possibly sale? 2) Who contributed how much equity and paid monthly installments? 3) Upon sale, the equity goes back to the respective person plus installments, and if the house then has an added value, I would split the remaining balance of the sale price minus equity/installments 50:50. I want to make it as fair as possible and not profit from my girlfriend.

Basically, marriage is not ruled out, but at the moment not in the plan.

I assume that with my income I can manage the monthly payments. The remaining financing still needs to be clarified, but I already have a commitment for €500K.

Land register in your name
Loan in your name, if your income is sufficient for the house construction

Contract for securing your girlfriend, which you should actually have anyway. She takes care of your child and you continue to work as usual.

If your income is not enough and your girlfriend has to be involved
now both in the land register (to avoid a later gift)
Loan agreement for both of you
Contract for case X to secure your equity
You have to make sure that she (we are now talking about a bitter divorce) cannot delay the payout/value transfer, for example because it is linked to a sale

If only you are in the land register and your girlfriend is later included, you trigger a gift.
Property value 100,000 belongs to you alone
later it belongs to both of you at 50%. That means you give her 50,000 euros = taxable gift

If your girlfriend has to be included in the loan, she should also be registered in the land register [GB]. What do you mean by the remaining financing? The amount over 500k? Separation allowance as well as maintenance are already regulated by law. You can design the contract however you want as long as it is not immoral. The ideas you mentioned are basically feasible but involve pitfalls (for her) regarding taxes since you are unmarried. In case of marriage, you would have a tax exemption of 500k€. So you could register your girlfriend in the land register without gift tax. It does not matter if she is included in the loan. Whether in community of accrued gains or marital property regime, the values brought into the marriage are secured, as are inheritances. Buy the property in your name. Then arrange everything regarding the financing. I would also think about the topic of marriage. At first, it can just be a civil ceremony. The big celebration can be held in the new house...

A marriage regulates many things (not everything) fairly and well There are regulations regarding - Accrued gains (earned by both, also because the wife supports the husband so he can continue working full-time and earning) - Pension share (part-time work later puts the wife at a disadvantage and there are no maintenance regulations for unmarried couples) - Assets before the marriage

Not to forget is also the inheritance. Are they mutual children or from a previous relationship? Had a similar case in the family but without children. Before buying the house, quickly got married civilly in a very small circle. The proper wedding was then this year. Made everything much easier.