(1) A Certificate of enrollment granted under rule 4 shall remain valid for so long as it is not cancelled under sub-rule (2) of rule 7.
(2) An application for amendment of certificate of enrollment shall be made in Form III to the prescribed authority. On receipt of such application the prescribed authority may require the applicant to furnish such additional informa tion or evidence as may be necessary for determining the aomunt of tax payable by the applicant according to the Schedule to the Act, and upon determination of the amount of tax payable by the applicant, the prescribed authority shall make necessary amendment in the certificate of enrollment under his dated signature indicating the year from which the tax at the revised rate shall be payable.
(3) Notwithstanding anything contained in sub-rule (2), where consequent upon the amendment of any of the items No. 2 or 3 of the schedule to the Act, the classification of persons or the rate of tax payable under the Act or both is or are changed and a new classification of persons or a new rate of tax or both is or are specified, than the classification of persons or the rate of tax payable or both as 4 mentioned in the last paragraph of the certificate of enrollment in Form III granted under rule 4 to the holders of such certificates prior to such amendment shall stand changed respectively to the new classification of person or the new rate of tax or both so specified in the Schedule with effect from the date of coming into force of such amendment.