The Internet pages of public administrations should contain a statement of accessibility (usually in a section called Accessibility) in which clearly indicates the information about the level of accessibility of the same, the date on which became the revision of the level of accessibility declared and a method of contact to communicate incidences of accessibility. However this statement does not need to be associated with a certification process.
Compliance with the rules of accessibility can be certified (optionally) through bodies certification. Specifically in the area English exist Spanish certification accessibility. There are also different companies that after a process of accessibility audit of a web portal offers the possibility to include in the portal their accessibility stamps individuals.