Banco de España, as any other Central Bank in the Eurosystem, takes care of the quality of banknotes in circulation, so that they stay in a good state of use that allows and eases economic interchange.
Those banknotes that come into Banco de España are thoroughly subjected to a recount, analysis, inspection, selection and sorting process. Finally, they are destroyed, if their state of use is considered inadequate, or packed and sealed for further circulation if their quality is high enough. In no case those banknotes which are broken, tore, dirty, painted, or without any of their chartacteristics are returned to circulation.
The afore mentioned process, which is known as "Notes Treatment", takes place in the Banco de España facilities using high technology sorting machines, which accomplish sorting, packing and even destruction with a high automatism degree.
The structure of the treatment system in Banco de España is based on a decentralized model, stablishing Regional Treatment Centers, located in the Banco de España branches.