JM 3-8.620
The appropriation, “Salaries and Expenses, United States Attorneys, Department of Justice,” is chargeable with the expense of operating the USAOs.
The date on which fees are earned, services rendered, orders are placed, or expenses incurred, and not the date of certification of payment, determine the fiscal year from which payment shall be made, except that bills for metered commodities or services such as electricity, telephone, etc., shall be paid from the appropriation current at the end of the billing period.
[updated February 2018]