N.Y. Comp. Codes R. & Regs. tit. 16, § 561.15 – Transactions with associated companies.

(a) Each utility shall keep its accounts and records so as to be able to furnish accurately and expeditiously statements of all transactions with associated companies. The statements may be required to show the general nature of the transactions, the amounts involved therein and the amounts included in each account prescribed herein with respect to such transactions. Transactions with associated companies shall be recorded in the appropriate accounts for transactions of the same nature. Nothing herein contained, however, shall be construed as restraining the utility from subdividing accounts for the purpose of recording separately transactions with associated companies.
(b) If a clearing account is not maintained for each associated company in which all gross charges by that company are entered and from which they are distributed, all charges of any nature whatsoever by any associated company shall be credited at the gross amounts involved to a subaccount for that company under the appropriate subdivisions of accounts for Advances from Associated Companies and Payables to Associated Companies, even though immediately transferred to an account for capital stock, long-term debt, or other liability. In like manner, in the absence of clearing accounts, all gross charges to any associated company shall be debited to a subaccount for that company under the appropriate subdivisions of accounts for Investments in Associated Companies and Receivables from Associated Companies, even though immediately transferred to a special deposit, special fund, other investment account, or other asset.
(c) Dividends, rebates, or earnings from associated companies or mutual service companies, representing refunds of the excess charges made by such companies over the cost to them, shall be debited to account 146, Accounts Receivable from Associated Companies, and shall be credited so far as practicable to the same accounts to which the corresponding charges were made, including proper distinction between construction and operating expenses. Credits applicable to operating expenses, where it is impracticable to allocate them among the accounts to which the corresponding charges have been made shall be recorded in account 929, Duplicate Charges-Credit.