Mass. Gen. Laws ch. 174A § 9
Every member of or subscriber to a rating organization shall adhere to the filings made on its behalf by such organization except that any such insurer may make written application to the commissioner for permission to file a deviation from the class rates, schedules, rating plans or rules respecting any kind of insurance, or class of risk within a kind of insurance, or combination thereof. Such application shall specify the basis for the modification and a copy thereof shall also be sent simultaneously to such rating organization. The commissioner shall set a time and place for a hearing at which the insurer and such rating organization may be heard and shall give them not less than ten days' written notice thereof. In the event the commissioner is advised by the rating organization that it does not desire a hearing he may, upon the consent of the applicant, waive such hearing. In considering the application for permission to file such deviation the commissioner shall give consideration to the available statistics and the principles for rate making as provided in section five. The commissioner shall issue an order permitting the deviation for such insurer to be filed if he finds it to be justified and it shall thereupon become effective. He shall issue an order denying such application if he finds that the resulting premiums would be excessive, inadequate or unfairly discriminatory. Each deviation permitted to be filed shall be effective for a period of one year from the date of such permission unless terminated sooner with the approval of the commissioner.
Mass. Gen. Laws ch. 174A, § 9