Hawaii Revised Statutes Division 2. Business § 431:10C-112

(a) In the case of cancellation or nonrenewal of a motor vehicle insurance policy by the insurer, the insurer shall mail a written notice of prospective cancellation or nonrenewal to the insured not fewer than thirty days prior to the effective date of the cancellation or nonrenewal. The insurer shall continue all motor vehicle insurance and optional additional coverages in force for thirty days following the mailing; provided that in the case of cancellation for the nonpayment of premiums the insurer shall:

Cancellation or nonrenewal shall not be deemed valid unless the mailing required by this section is supported by a certificate of mailing properly validated by the United States Postal Service.

(b) If the insurer has manifested in writing an offer to renew to the named insured at least thirty days prior to the end of the policy period and the offer is not accepted before the expiration of the policy term, the policy shall lapse upon that expiration date and section 431:10C-111 shall not apply. Notwithstanding other valid methods of acceptance, an offer shall be deemed accepted as of the date of mailing of the acceptance. The date of mailing may be evidenced by the postmark or a certificate of mailing properly validated by the United States Postal Service.