[Claim for Mileage Reimbursement for Use of Privately Owned Vehicle]

A GAO decision was requested as to whether an employee who used his privately owned vehicle in lieu of a common carrier for temporary duty travel could be reimbursed on a round-trip mileage basis in an amount not to exceed the estimated travel cost indicated on his travel orders. This estimated amount was higher than the constructive cost of the air transportation that the employee would have been reimbursed for by the transportation officer. An employee who travels by a privately owned vehicle as a matter of personal preference is entitled to mileage reimbursement limited to the cost of travel by common carrier, including applicable per diem. GAO found that, since the travel officer properly routed the travel, the employee's mileage reimbursement was properly limited to the cost of air carrier transportation so routed. Accordingly, the the amount shown in the employee's travel orders as an estimated cost created no additional entitlement.