(1) Every backbill shall contain a written explanation of the reason for the backbill that shall be sufficiently detailed to apprise the customer of the circumstances, error or condition that caused the underbilling, and, if the backbill covers more than a 24-month period, a statement setting forth the reason(s) the utility did not limit the backbill under subdivision (c) of this section.

(2) Every backbill shall contain, or be accompanied by, all required information applicable under section 13.11 of this Part.

(3) Every backbill covering more than a one-month period, other than a catch-up backbill, shall contain a notice that the customer may obtain upon request a detailed billing statement showing how the charges were calculated, including any late payment charges. All catch-up backbills shall clearly indicate how the backbill was calculated, whether as if the service were used during the current cycle, or as if redistributed back to the last actual reading.

(4) A backbill shall be accompanied by an offer of a deferred payment agreement in accordance with section 13.5 of this Part, if applicable.

(1) A utility shall not render a backbill more than six months after the utility actually became aware of the circumstance, error or condition that cause the underbilling, unless a court extends the time to render a backbill.

(2) A utility shall not upwardly revise a backbill unless the first backbill explicitly stated that the utility reserved the right to do so, the revised backbill is rendered within 12 months after the utility actually became aware of the circumstance, error or condition that caused the underbilling, and:

(3) A utility shall render a downwardly revised backbill as soon as reasonably possible and within two months after the utility becomes aware that the first backbill was excessive.

(4) A utility shall not render a backbill for any underbilling when the reason for the underbilling is apparent from the customer's service application, or could have been revealed in a service application and the utility failed to obtain and retain one.

(1) When the failure to bill at an earlier time was due to utility deficiency, a utility shall not bill a customer for service rendered more than 12 months before the utility actually became aware of the circumstance, error or condition that caused the underbilling, unless the utility can demonstrate that the customer knew or reasonably should have known that the original billing was incorrect.

(2) A utility shall not bill a customer for service rendered more than 24 months before the utility actually became aware of the circumstance, error or condition that cause the underbilling, unless the utility can demonstrate that the customer knew or reasonably should have known that the original billing was incorrect.

(1) A utility shall not upwardly revise an estimated demand unless it can demonstrate that, for the period during which the demand was estimated, it complied with the meter-reading requirements and the no-access procedures of section 13.8 of this Part.

(2) All revised demands shall be based on the best available information, including the customer's present and historical energy consumption and load factor.

(3) No revised demand shall exceed 95 percent of the subsequent actual demand, unless the utility has, along with the estimated demand bill, offered a special appointment to read the meter, and the customer failed to arrange and keep such appointment, in which case the estimated demand may be revised up to the level of the subsequent actual demand.

(4) A utility shall downwardly revise any estimated demand that exceeds the subsequent actual demand, which 30 calendar days after such actual demand was obtained.

(5) A utility may only upwardly revise an estimated demand within 60 calendar days after the subsequent actual demand was obtained.