Section 6. (a) Every insurer shall file with the commissioner or his designated representative every manual of classifications, rules and rates, every rating plan and every modification of any of the foregoing which it proposes to use. Every such filing shall be made with the commissioner at least fifteen days prior to the proposed effective date thereof and shall indicate the character and extent of coverage contemplated and the extent and nature of any change in rates, rating plans or premium charges. The commissioner may by order delay the effective date for not more than thirty additional days in any case where he determines such delay is needed to properly examine the filing and any supporting information filed as requested or to permit a hearing thereon; provided further, however, that, if such filing is made by a medical malpractice insurer with respect to medical malpractice insurance, the commissioner may further delay the effective date of such filing for not more than ninety additional days. The commissioner may require such insurer to furnish the information upon which it supports such filing. Any filing may be supported by (1) the experience or judgment of the insurer or rating organization making the filing, (2) the experience of other insurers or rating organizations, or (3) any other factors which the insurer or rating organization deems relevant. A filing and any supporting information shall be open to public inspection after the filing becomes effective.

(b) An insurer may satisfy its obligation to make such filings by becoming a member of, or a subscriber to, a licensed rating organization which makes such filings, and by authorizing the commissioner to accept such filings on its behalf; provided, that nothing contained in this chapter shall be construed as requiring any insurer to become a member of or a subscriber to any rating organization.

(c) Under such rules and regulations as he shall adopt the commissioner may, by written order, suspend or modify the requirement of filing as to any kind of insurance, subdivision or combination thereof, or as to classes of risks, the rates for which cannot practically be filed before they are used. Such orders, rules and regulations shall be made known to insurers and rating organizations affected thereby. The commissioner may make such examination as he may deem advisable to ascertain whether any rates affected by such order meet the standards set forth in subdivision 4 of subsection (a) of section five.

(d) Upon the written application of the insured, stating his reasons therefor, filed with and approved by the commissioner, a rate in excess of that provided by a filing otherwise applicable may be used on any specific risk.

(e) Beginning ninety days after the effective date of this chapter no insurer shall make or issue a contract or policy except in accordance with filings made by or for said insurer as provided in this chapter or in accordance with subsection (c) of this section.

(f) Filings may consist of manuals of classifications, rules and rates, and rating plans providing for indivisible rate or single premium for policies or contracts of insurance, including policies or contracts of insurance issued by such insurers under the authority of section twenty-two A of chapter one hundred and seventy-five and providing coverage against the hazards specified in more than one of the clauses or subdivisions of section forty-seven of said chapter one hundred and seventy-five.