According to Article 86 of Law 8/1997, of December 23, 1997,
1. When the deposit of the deposit is made after the established deadline but before the start of the inspection, a surcharge of 20% shall be demanded, excluding the penalties that might otherwise have been demanded, but not the interest on late payment. However, if the payment is made within three, six or twelve months following the end of the voluntary payment period, a single surcharge of 5, 10 or 15%, respectively, will be applied, excluding interest on late payment and any penalties that might otherwise have been imposed.
If, during the course of the administrative action, non-compliance with the obligation to deposit the bond is detected, in addition to the amount thereof, interest for late payment and any penalties that may be applicable, as the case may be, shall be demanded.
3. Upon expiration of the term for payment in the voluntary period without having been made, its collection shall be carried out by means of the enforcement procedure, in accordance with the general provisions regulating said procedure.