Code of Federal Regulations Title 18. Conservation of Power and Water Resources § 18.367.1730 Account 173, Accrued revenues

At the option of the service company, the estimated amount accrued for service rendered, but not billed at the end of any accounting period, may be included in this account. In case accruals are made for unbilled revenues, they must be made likewise for unbilled expenses, such as for the purchase of energy.