Willo, you don’t get it. X buys green land from y via a notary. In the F plan, it is green land. Period. That costs amount z. Plus tax. Period. What x and y have in the back of their minds doesn’t initially affect this deal at all, later on no notary is needed for that, just a simple invoice. There is also a risk involved: if it remains green land, it remains as such. No claim for an F plan change is registered with the notary. It can also be done more officially. X buys green land from y via a notary with a clause in the contract that if by such and such day this land becomes building land, y is to be involved in the increase in value with amount such and such. It’s just more complicated. Karsten