Notwithstanding any general or special law to the contrary, carriers offering small group health insurance plans, including carriers licensed under chapters 175, 176A, 176B or 176G, shall file small group product base rates and any changes to small group rating factors that are to be effective on January 1 of each year, on or before July 1 of the preceding year. The commissioner shall approve, modify or disapprove any proposed changes to base rates; provided, however, that the commissioner shall only modify or disapprove any proposed changes to base rates that are excessive, inadequate or unreasonable in relation to the benefits charged. The commissioner shall disapprove any change to small group rating factors that is discriminatory or not actuarially sound. Rates of reimbursement or rating factors included in the rate filing materials submitted for review by the division shall be deemed confidential and exempt from the definition of public records in clause Twenty-sixth of section 7 of chapter 4.