48 CFR 13.305-3: 13.305-3 Conditions for use.

Imprest funds or third party drafts may be used for purchases when—

(a) The imprest fund transaction does not exceed $500 or such other limits as have been approved by the agency head;

(b) The third party draft transaction does not exceed $2,500, unless authorized at a higher level in accordance with Treasury restrictions;

(c) The use of imprest funds or third party drafts is considered to be advantageous to the Government; and

(d) The use of imprest funds or third party drafts for the transaction otherwise complies with any additional conditions established by agencies and with the policies and regulations referenced in 13.305-1.