The Act on the Public Statistical Function stipulates that the statistics for the compilation of which data are required on a compulsory basis are to be established by law. For this reason, in 1990, an additional provision was published in the General State Budget Act providing a detailed list of all statistics where the obligation to cooperate is established.
Given that over time, this list was incomplete, in 1996 it was modified by Law, including the statistics included in the National Statistical Plan and those that were obligatory for the Spanish State due to the requirements of European Union regulations.