A surveillance audit is carried out once a year within the three-year validity period and recertification audit will be conducted at the expiry of the three-year period.
Because this exam gives your employer better understanding of your ability, and Cambridge exams don't have an expiration date so as soon as you get your result, it will stay with you forever.
The additionality of a project, the certainty with which you know that carbon will be avoided or removed, the duration of time over which your investment will remain valid.