(a) Authorized rates. Bills must be calculated according to the rates approved by the regulatory authority and listed on the utility's approved tariff. Unless specifically authorized by the commission, a utility may not apply a metered rate to customers in a subdivision or geographically defined area unless all customers in the subdivision or geographically defined area are metered.
(b) Due date.
  (1) The due date of the bill for utility service may not be less than 16 days after issuance unless the customer is a state agency. If the customer is a state agency, the due date for the bill may not be less than 30 days after issuance unless otherwise agreed to by the state agency. The postmark on the bill or the recorded date of mailing by the utility if there is no postmark on the bill, constitutes proof of the date of issuance. Payment for utility service is delinquent if the full payment, including late fees and regulatory assessments, is not received at the utility or at the utility's authorized payment agency by 5:00 p.m. on the due date. If the due date falls on a holiday or weekend, the due date for payment purposes is the next work day after the due date.
  (2) If a utility has been granted an exception to the requirements for a local office in accordance with §24.153(d)(3) of this title (relating to Customer Relations), the due date of the bill for utility service may not be less than 30 days after issuance.
(c) Penalty on delinquent bills for retail service. Unless otherwise provided, a one-time penalty of either $5.00 or 10% for all customers may be charged for delinquent bills. If, after receiving a bill including a late fee, a customer pays the bill in full except for the late fee, the bill may be considered delinquent and subject to termination after proper notice under §24.167 of this title (relating to Discontinuance of Service). An additional late fee may not be applied to a subsequent bill for failure to pay the prior late fee. The penalty on delinquent bills may not be applied to any balance to which the penalty was applied in a previous billing. No such penalty may be charged unless a record of the date the utility mails the bills is made at the time of the mailing and maintained at the principal office of the utility. Late fees may not be charged on any payment received by 5:00 p.m. on the due date at the utility's office or authorized payment agency. The commission may prohibit a utility from collecting late fees for a specified period if it determines that the utility has charged late fees on payments that were not delinquent.
(d) Deferred payment plan. A deferred payment plan is any arrangement or agreement between the utility and a customer in which an outstanding bill will be paid in installments. The utility shall offer a deferred payment plan to any residential customer if the customer's bill is more than three times the average monthly bill for that customer for the previous 12 months and if that customer has not been issued more than two disconnection notices at any time during the preceding 12 months. In all other cases, the utility is encouraged to offer a deferred payment plan to residential customers who cannot pay an outstanding bill in full but are willing to pay the balance in reasonable installments. A deferred payment plan may include a finance charge that may not exceed an annual rate of 10% simple interest. Any finance charges must be clearly stated on the deferred payment agreement.
(e) Rendering and form of bills.
  (1) Bills for water and sewer service shall be rendered monthly unless otherwise authorized by the commission, or unless service is terminated before the end of a billing cycle. Service initiated less than one week before the next billing cycle begins may be billed with the following month's bill. Bills shall be rendered as promptly as possible following the reading of meters. One bill shall be rendered for each meter.
  (2) The customer's bill must include the following information, if applicable, and must be arranged so as to allow the customer to readily compute the bill with a copy of the applicable rate schedule:
    (A) if the meter is read by the utility, the date and reading of the meter at the beginning and at the end of the period for which the bill is rendered;
    (B) the number and kind of units metered;
    (C) the applicable rate class or code;
    (D) the total amount due for water service;
    (E) the amount deducted as a credit required by a commission order;
    (F) the amount due as a surcharge;
    (G) the total amount due on or before the due date of the bill;
    (H) the due date of the bill;
    (I) the date by which customers must pay the bill in order to avoid addition of a penalty;
    (J) the total amount due as penalty for nonpayment within a designated period;
    (K) a distinct marking to identify an estimated bill;
    (L) any conversions from meter reading units to billing units, or any other calculations to determine billing units from recording or other devices, or any other factors used in determining the bill;
    (M) the total amount due for sewer service;
    (N) the gallonage used in determining sewer usage; and
    (O) the local telephone number or toll free number where the utility can be reached.
  (3) Except for an affected county or for solid waste disposal fees collected under a contract with a county or other public agency, charges for nonutility services or any other fee or charge not specifically authorized by the Texas Water Code or these rules or specifically listed on the utility's approved tariff may not be included on the bill.
(f) Charges for sewer service. Utilities are not required to use meters to measure the quantity of sewage disposed of by individual customers. When a sewer utility is operated in conjunction with a water utility that serves the same customer, the charge for sewage disposal service may be based on the consumption of water as registered on the customer's water meter. Where measurement of water consumption is not available, the utility shall use the best means available for determining the quantity of sewage disposal service used. A method of separating customers by class shall be adopted so as to apply rates that will accurately reflect the cost of service to each class of customer.
(g) Consolidated billing and collection contracts.
  (1) This subsection applies to all retail public utilities.
  (2) A retail public utility providing water service may contract with a retail public utility providing sewer service to bill and collect the sewer service provider's fees and payments as part of a consolidated process with the billing and collection of the water service provider's fees and payments. The water service provider may provide that service only for customers who are served by both providers in an area covered by both providers' certificates of public convenience and necessity. If the water service provider refuses to enter into a contract under this section or if the water service provider and sewer service provider cannot agree on the terms of a contract, the sewer service provider may petition the commission to issue an order requiring the water service provider to provide that service.
  (3) A contract or order under this subsection must provide procedures and deadlines for submitting filing and customer information to the water service provider and for the delivery of collected fees and payments to the sewer service provider.
  (4) A contract or order under this subsection may require or permit a water service provider that provides consolidated billing and collection of fees and payments to:
    (A) terminate the water services of a person whose sewage services account is in arrears for nonpayment; and
    (B) charge a customer a reconnection fee if the customer's water service is terminated for nonpayment of the customer's sewage services account.
  (5) A water service provider that provides consolidated billing and collection of fees and payments may impose on each sewer service provider customer a reasonable fee to recover costs associated with providing consolidated billing and collection of fees and payments for sewage services.
(h) Overbilling and underbilling. If billings for utility service are found to differ from the utility's lawful rates for the services being provided to the customer, or if the utility fails to bill the customer for such services, a billing adjustment shall be calculated by the utility. If the customer is due a refund, an adjustment must be made for the entire period of the overcharges. If the customer was undercharged, the utility may backbill the customer for the amount that was underbilled. The backbilling may not exceed 12 months unless such undercharge is a result of meter tampering, bypass, or diversion by the customer as defined in §24.169 of this title (relating to Meters). If the underbilling is $25 or more, the utility shall offer to such customer a deferred payment plan option for the Cont'd...