Assessment of unregistered persons

of section 29 but who is liable to pay tax, the proper officer may proceed to assess the tax liability of such taxable person to the best of his judgment for the relevant tax periods and issue an assessment order within a period of five years from the date specified under section 44 for furnishing of the annual return for the financial year to which the tax not paid relates: Provided that no such assessment order shall be passed without giving the person an opportunity of being heard