[IRS Authority to Retroactively Compensate Employees for Travel Expenses]

The Department of the Treasury requested an advance decision concerning the Internal Revenue Service's (IRS) authority to retroactively pay its non-bargaining unit employees for travel expenses to reflect a change in the procedures for computing such expenses. GAO held that there was no statutory authority to apply the amended procedure for the period prior to the regulation's effective date. Accordingly, IRS should not retroactively compensate its non-bargaining employees for the difference between the rates.