301-10.117—May I keep compensation an airline gives me for voluntarily vacating my seat on my scheduled airline flight when the airline asks for volunteers?

Yes:

(a) If voluntarily vacating your seat will not interfere with performing your official duties; and

(b) If additional travel expenses, incurred as a result of vacating your seat, are borne by you and are not reimbursed; but

(c) If volunteering delays your travel during duty hours, your agency will charge you with annual leave for the additional hours.

CFR