House sale - how to approach it best?

Oh, a rent-free right of residence. Then yes.

In order to still have 300K after rent, I either have to sell the place for 312K. That means more charges for the buyer. Or I sell for 300K, and after paying rent I only have 288K left in my pocket. (End quote) Exactly. The contract then states 288 thousand. The rent-free right of residence costs 12 thousand. This is what the rent also costs if I achieve 300 and take the apartment for 12 months. Only the tax is then due on 288. The rest is arranged in a binding side agreement. Karsten

That's a good solution!

The advantage of this construction, which is a win-win: The buyer saves taxes and notary fees. The seller saves having to move temporarily into a holiday apartment and can stay in their old house. You can't have everything. I can't expect the buyer to let me live there for free for 12 months, even though it is now his house. You have to offer him a little incentive.

Nevertheless, the simplest version is to conclude the notarized contract and agree on a handover 10 months later, with the purchase price payment taking place then. This way, all rights and obligations transfer to the buyer at the correct time.

If nothing is agreed upon, the buyer would otherwise have to clear snow in front of your door in winter, for example. After all, it would already be his house. What will you do if he terminates the rental agreement after the purchase due to personal use?

What do you do if he terminates the lease due to personal use after the purchase?

There is no lease agreement in this arrangement. That would mean the buyer would have to declare any rental income for tax purposes. They try to avoid this with the free right of use.

Here everyone is talking past each other.

The only clean solution is the one proposed by markus2703.
Transfer AND payment of the purchase price at a correspondingly later date.
What Arifas envisions, however, is payment of the purchase price significantly BEFORE the transfer. This makes the whole thing quite complicated and will deter many potential buyers.

Furthermore, the buyer virtually bears the seller’s 'construction risk.'
There are hardly any house constructions that proceed as planned. The buyer will most likely have to wait longer for the move-out than originally planned.

I would not buy in such a constellation. The seller will also achieve significantly more interested parties and a higher purchase price if he handles the whole thing cleanly (i.e., with bridge financing).