301-75.202—What must we do if the interviewee exchanges the ticket he or she has been issued?

If You will inform the traveler
The new ticket is more expensive than the ticket you provided That he/she must pay the difference using personal funds and he/she will not receive reimbursement for the extra amount.
The new ticket is less expensive than the ticket you provided Provide the interviewee with a credit/refund address by attaching a copy of the GTR, or some other document containing this information, to either the ticket or the travel authorization as provided in U.S. Government Passenger Transportation Handbook (http://fss.gsa.gov/transtrav/usgpth.pdf)

Code of Federal Regulations

[FTR Amdt. 70, 63 FR 15980, Apr. 1, 1998; 63 FR 35538, June 30, 1998, as amended by FTR Amdt. 108, 67 FR 57968, Sept. 13, 2002]