32 CFR 228.16: Soliciting, vending, and debt collection.

Commercial or political soliciting, vending of all kinds, displaying or distributing commercial advertising, collecting private debts or soliciting alms on protected property is prohibited. This does not apply to:

(a) National or local drives for welfare, health, or other purposes as authorized by the “Manual on Fund Raising Within the Federal Service,” issued by the U.S. Office of Personnel Management under Executive Order 12353, 47 FR 12785, 3 CFR, 1982 Comp., p. 139, or by other federal laws or regulations; and

(b) Authorized employee notices posted on Agency bulletin boards.