Generally, the ISO9001 certificate is valid for 3 years;

But the premise is that the company must accept the supervision and audit of the certification body, that is, the annual audit;

The frequency of supervision and review is generally once every 12 months, that is, once a year, so it is called annual review;

Some companies may be special. The certification body requires an annual review every 6 months or 10 months;

ISO certification audits will be notified in advance, some certifications are flight inspections, that is, they may arrive at the factory for unannounced inspections at any time without notification.