(1) Where an insurer has, in accordance with clause 147, furnished a certificate to an employer or another insurer for the purpose of ascertainment of the premium payable in respect of a period of insurance, the particulars relating to costs of claims specified in the last or only certificate so furnished are binding on the employer and any insurer for the purpose of calculation at any time of those costs of claims as at the commencement of that period of insurance, except as provided by subclause (2).
(2) If an insurer (other than the insurer who furnished the certificate) does not agree with any of those particulars and applies to the Authority for a variation of those particulars (and the application is not withdrawn or, in the opinion of the Authority, abandoned), the particulars relating to costs of claims specified in the certificate as confirmed or varied by the Authority are binding on any insurer for the purpose of calculation at any time of those costs of claims as at the commencement of that period of insurance.