PAYE54015 - Employer returns: regulation 80 determinations: time limits and appeals: regulation 80(5): parts IV and V TMA 1970

The rules about time limits and appeals apply to a determination just as to an assessment. Apply them as if you had assessed the employer. You may sometimes need to determine tax for a year outside the normal time limit. If so, PAYE54300 tells you the special steps to take.