(a) This account must include all expenses, properly included in service company operating expenses, incurred by the service company in connection with formal cases before regulatory commissions, or other regulatory bodies, on its own behalf or on behalf of associate companies, including payments made to a regulatory commission for fees assessed to the service company for pay and expenses of such commission, its officers, agents and employees, and for filings or reports made under regulations of regulatory commissions. The service company must be prepared to show the cost of each formal case. The following items must be included in this account:

(1) Salaries, fees, retainers, and expenses of counsel, solicitors, attorneys, accountants, engineers, clerks, attendants, witnesses, and others engaged in the prosecution of, or defense against petitions or complaints presented to regulatory bodies.

(2) Office supplies and expenses, payments to public service or other regulatory commissions, stationery and printing, traveling expenses, and other expenses incurred directly in connection with formal cases before regulatory commissions.

(b) Exclude from this account and include in other appropriate operating expense accounts, expenses incurred in the improvement of service, additional inspection, or rendering reports, which are made necessary by the rules and regulations, or orders, of regulatory bodies.