The inheritance tax is assigned to the Autonomous Communities. There is national framework legislation on which each Community can introduce the changes it deems appropriate.
This generates great differences between the different regions of Spain, having at one extreme those in which there are bonuses of up to 99%, when the heirs are family in direct ascending or descending line, to those in which the tax can even be higher than what the state standard establishes, which is already characterized by being quite burdensome.
If you move to Spain, take into account the Autonomous Community of residence, it is essential when establishing the obligations and the amount of taxes before an inheritance.