6. Amendment of certificate of enrolment.-

 (1) The certificate of enrolment granted under Rule 4 shall remain valid so long as it is not cancelled under sub-rule (2) of Rule-7.

(2) An application for a revised certificate of enrolment shall be made in Form-2. On receipt of such application the assessing authority may call upon the applicant to furnish such additional information in evidence as may be necessary for determining the amount of tax payable by him according to the Schedule to the Act and after so determining the amount of tax payable by the applicant, the assessing authority shall make necessary amendments, in the certificate of enrolment under his dated signature indicating the year from which the tax at the revised rate shall be payable.