How long must I wait before I can re-sit my examination?

Please see the following table for the resit criteria for each CREST examination:

Note:
a) If a candidate fails an examination that comprises two parts, both parts must be retaken.
b) For examinations marked with an *, if a candidate is unsuccessful on their fourth attempt, they must wait six
months before they can re-attempt the examination at which point they will have a further four attempts
available to them.

I.e.: 4 attempts, all fail = six-month break. Further 4 attempts, all fail = six-month break. And so on.

If there is an unenforced six-month break, candidates will have four attempts before this policy is applied.