If an applicant does not pass the exam, they may take the test again but must pay the fee again. There is no limit to the number of times an applicant can take the exam, and there is no minimum wait time before requesting a retest.
If a person needs to retake the exam, they would have received a new pre-registration form with their exam scores. That form needs to be completed and sent back to ICB with the exam fee. A person has 1 year from the date they last took the exam to retest. If they do not test in a year’s time, then their file will expire, and they will need to reapply with a new application.