Crediting Collections to Appropriations

A State Department traveler was authorized to travel from Washington, D.C., to Milan, Italy. That travel could have been performed on American flag airlines at a cost of $386 ($383 plus $3 tax.) The traveler, however, wanted to stop in Paris for personal reasons and that required the use of a foreign flag carrier from Paris to Milan. That travel cost the State Department the same as the direct travel $386 ($383 plus $383 tax.) State Department determined that there was no justification for the use of foreign flag carriers and disallowed $79.37 as a pro rata share of the through fare. The $79.37 was credited back to the State Department's travel funds. Should the disallowed amount be credited to the agency's appropriation or miscellaneous receipts?