This is a special printing issued by the franking scales Epelsa-Iris but it can't be used as a franking.

On 1st of January, 2002 the postal tariffs in Spain were changed and this included the rates for printed matter of more than 500 units. This change here was no longer based solely on the weight. From this date the postage was the result of a complex calculation based on the number of objects posted, the total weight, the destination, and possibly other factors. The result then establishes the postal tariff, to 3 decimal places.
 

	The system then ignores the third decimal place and the franking scale issues the ATM printed to two decimal places. The third decimal value is then multiplied by the total number of items for posting, and a value for the residual amount is issued as a label with the date on, and the Spanish word REGULARIZA (regularize) printed in the centre.

This is one of the origins of this type of stamp, but it's possible that other postal operations realized from the franking scales with the IRIS system generate residual franking values that end at the automatic issue of a regularization stamp.
 

Detail - Special printing REGULARIZA

	This rare stamp, it's NOT an ATM because of its special characteristics and use. It is only for internal use in post offices and is unlikely to come into the hands of collectors.
Collaboration: J. Mestre and M. Juanes