You must provide:
(a)
Evidence of your necessary travel authorizations including any necessary special authorizations;
(1)
Any lodging expense, except when you are authorized a fixed reduced per diem allowance;
(2)
Any other expense costing over $75. If it is impracticable to furnish receipts in any instance as required by this subtitle, the failure to do so must be fully explained on the travel voucher. Mere inconvenience in the matter of taking receipts will not be considered; and
Code of Federal Regulations
[FTR Amdt. 70, 63 FR 15969, Apr. 1, 1998, as amended by 67 FR 57966, Sept. 13, 2002; FTR Amdt. 2007-05, 72 FR 61539, Oct. 31, 2007]