Two per year
Honestly, I have no idea about costs regarding our ISO certification. I am the new kid here - was hired Sept. 10 to be Mgt. Rep., Doc. Controller, and all-around ISO guru for the Oct. 6 Surveillance Audit. Made it through with flying colors despite my incredible lack of previous ISO experience.
All costs were negotiated before my arrival. I was not involved with the selection of consultants, registrars, etc. It is my perception that we get billed for two man days every 6 months - one day for the external auditor to audit HQ and the other day for him to visit one branch.
I didn't know it was uncommon to have surveillance audits every 6 months. I learn all kinds of things when I visit this forum!