41 CFR § 301-10.114
What must I do with unused Government Transportation Request(s) (GTR(s)), ticket(s) or refund application(s)?
June 9, 2020
You must submit any unused GTR(s), unused ticket coupons, unused e-tickets, or refund applications to your agency in accordance with your agency's procedures.
[FTR Amdt. 108, 67 FR 57964, Sept. 13, 2002]