1. (1) Every backbill must contain a written explanation of the specific reason for the backbill, and if the bill covers more than a 24-month period, a statement as to why the billing was not limited under subdivision (c) of this section.
2. (2) Every backbill must contain all required information applicable under section 14.15 of this Part.

3. (3) A backbill must be accompanied by an offer of a payment agreement in accordance with section 14.10 of this Part, if applicable.

   (b) Limitations on issuance of backbills.

4. (1) A utility may not issue a backbill more than six months after the utility actually became aware of the circumstance, error or condition that caused the underbilling.

5. (2) A utility may not upwardly revise a backbill, and must issue a downwardly revised backbill as soon as reasonably possible and within two months after the utility becomes aware that the first backbill was excessive.

   (c) Limitations on backbilling period.

6. (1) When the failure to bill earlier was due to utility deficiency, a utility must limit the backbilling period to 12 months before the utility actually became aware of and corrected the circumstance, error or condition that caused the underbilling, unless the utility can demonstrate that the customer's culpable conduct caused or contributed to the original underbilling.
7. (2) When the failure to bill earlier was not due to utility deficiency, a utility must limit the backbilling period to 24 months before the utility actually became aware of and corrected the circumstance, error or condition that caused the underbilling, unless the utility can demonstrate that the customer's culpable conduct caused or contributed to the original underbilling.

(a) Notice.