21. Action for default by an enrolled person.-

If a person liable to pay tax has failed to get himself enrolled, then without prejudice to the action that may be taken against him under sub-section (5) of section 5, the prescribed authority shall after giving the person a reasonable opportunity of being heard and after such inquiry as may be deemed fit, or otherwise assess the tax due to the best of his judgement and serve on him a notice of demand in Form XIV to pay the tax within fifteen days of the receipt of the notice. Notice of hearing in such case shall be issued by the prescribed authority in Form XIII. The notice under sub-section (6) of section 5 in respect of persons liable for enrollment shall also be in Form XIII.