Assessment of unregistered persons :

Where a taxable person fails to obtain registration even though liable to do so, the proper officer may proceed to assess the tax liability of such taxable person to the best of his judgement for the relevant tax periods and issue an assessment order within a period of five years from the due date for filing of the annual return for the year to which the tax not paid relates:

Provided that no such assessment order shall be passed without giving a notice to show cause and without giving the person a reasonable opportunity of being heard.