15. Rectification of mistakes

(1) any authority under this Act may, of his own motion or on an application being made in this behalf,  rectify any mistake apparent on the face of the record.

(2) Any authority under this Act, may review his own order, if any employer has been under-assessed for any period:

Provided that, if an order under this section has an adverse effect on an employer or a person, no such order shall be passed unless a reasonable opportunity of being heard has been given to such employer or person:

Provided further that, no order under this section shall be passed after the expiry of three years from the passing of the impugned order.