(6)Where, after the commencement of this Act, the mutawalli of a waqf fails to submit a return of the net annual income of the waqf within the time specified therefor or submits a return which, in the opinion of the Chief Executive Officer is incorrect or false in any material particular, or which does not comply with the provisions of this Act or any rule or order made thereunder, the Chief Executive Officer may assess the net annual income of the waqf to the best of his judgment or revise the net annual income as shown in the return submitted by the mutawalli and the net annual income as so assessed or revised shall be deemed to be the net annual income of the waqf for the purposes of this section:Provided that no assessment of net annual income or revision of return submitted by mutawalli shall be made except after giving a notice to the mutawalli calling upon him to show cause, within the time specified in the notice, as to why such assessment or revision of the return shall not be made and every such assessment or revision shall be made after considering the reply if any, given by the mutawalli.