Mass. Gen. Laws ch. 255C § 21
Upon the cancellation of an insurance contract the insured shall be entitled to a refund of the finance charges, such refund to be computed on a method which is at least as favorable to the insured as the actuarial method, so-called, from the effective date of cancellation irrespective of the time when the premium finance agency is reimbursed by the insurer or insurers. Whenever the gross unearned premiums received from the insurer or insurers are insufficient to extinguish the unpaid amount financed owed to the premium finance agency it may charge and collect a finance charge for the remaining unpaid amount financed not to exceed the rates established pursuant to the provisions of section one hundred and sixty-two B of chapter one hundred and seventy-five in effect on the date of cancellation and from said date to the time when the insured shall pay such balance. A premium finance agency shall give notice of cancellation to the policyholder by delivering such notice in hand to the named policyholder, or by leaving at his last business, residence or other address known to the agency, or by forwarding such notice to said address by first class mail, postage prepaid, and a notice delivered, so left or forwarded, shall be deemed a sufficient notice. No written notice of cancellation shall be deemed effective when mailed by the agency unless the agency obtains a certificate of mailing receipt from the United States Postal Service showing the name and address of the policyholder stated in the policy, but any notice of the intent to cancel as required by section thirty-four K of chapter ninety may be given by first class mail. If a premium finance agency, or any holder of a premium finance agreement, acting under a power of attorney in connection with the cancellation of a motor vehicle liability policy, as defined in section thirty-four A of chapter ninety, gives notice of cancellation in accordance with section thirty-four K of said chapter ninety, and thereafter the insured pays the full amount then due under the premium finance agreement, such agency or holder shall forthwith notify the insurer that it is revoking the notice of cancellation. Such notice of revocation shall not be binding upon the insurer, unless it is in writing and is received by the insurer not less than three days prior to the effective date of cancellation.
Mass. Gen. Laws ch. 255C, § 21