It is advisble to request in advance a valuation to the Regional Tax Agency (ATIB in the Balearic Islands). It usually takes between one and two months. There are two different forms depending on the location of the real estate (rustic or urban land). The Tax Agency will set a value so any price over that value declared in an official document (a purchase deed) will be usually accepted by the Regional tax Agency for transfer tax purposes (ITP). Please note that gain tax is State competition so this valuation by the Regional agency has very limited effects before the National Tax Agency.