account expiration attribute

Hi all, What RADIUS attribute would suit to account expiration? the context: - prepaid users must regularily add credit to his account - big credit -> big validity extension - small credit -> small validity extension - no account removal, just auth reject if validity date passed Credit adding and account validity extension is not managed by the RADIUS stuff, it's about a manual external insert What we just need is the right RADIUS attribute to be checked during auth, in order to reject if the date is passed. Thanks for any help. -- Architecte Informatique chez Blueline/Gulfsat: Administration Systeme, Recherche & Developpement +261 34 29 155 34