All utilities that choose to charge customers a fee for nonpayment due to returned payment may charge the customer the greater of $5.00 per account to which the returned payment applies or the amount that the bank charges the utility, not to exceed $20.00. If the utility charges the customer more than $5.00, the utility shall furnish the customer with proof of the bank charge. Any utility which chooses to impose a charge for returned payment must file terms and conditions that conform to this rule.
65-407 C.M.R. ch. 870, § 3