Policies may be changed by endorsement. All requests for endorsements must be in writing. The premium for the change shall be pro-rated to the end of the policy term, and an endorsement will be issued with the amount of the additional premium or return premium shown thereon. Payments are due within 30 days of receipt for endorsements with additional premiums. It is important that the remittance include the policy number and name of the insured so that the payment can be applied correctly. Refund checks for endorsements with return premiums will be forwarded to the broker within 30 days of issuance of the endorsement.