Are development costs included as a percentage in the calculation of additional costs?

For me, it was only the purchase price of the property

That depends:confused: What does the purchase contract say? If only the pure purchase price of the property is stated, the development costs are excluded. If an overall item is formed, the total amount must be used as the basis. Are you buying from a private individual, the city, or the company that is also carrying out the development?

P.S. I assume that it is not the internal development.

OK, I hope that I can still "manage" the purchase agreement and remove the development costs from it. I can't say whether the company I would buy from carries out the development. I will clarify.