(1) Rates for insurance under 211 CMR 131.00 must be filed with the Commissioner, and are subject to the requirements of M.G.L. c. 175A.(2) Loss costs for insurance under 211 CMR 131.00 must be filed with the Commissioner and must satisfy the requirements of SRB Bulletin 90-05 (Insurance Rating Organizations: Implementation of Loss Costs Filing Procedures) or any superseding bulletin, rule, or regulation.(3) Filings under 211 CMR 131.00 must include full justification for proposed rates, loss costs, or buyback coverage, and must be accompanied by all actuarial data used in their formulation, such as: (a) Historical exposure and claim data (both in number and in dollar amount, paid as well as incurred), including information relative to claims closed both with and without indemnity payments, for the previous five years.(b) Projected claims costs underlying the proposed loss costs, along with supporting documentation.(c) A narrative explanation of actuarial assumptions used in developing the loss costs.(4) Each rate or loss cost filing must be made at least 15 days prior to its proposed effective date. The Commissioner may delay the effective date for 30 additional days if he or she determines the delay is necessary to properly examine the filing or to request any supporting information or to permit a hearing on the filing.