5 CFR 5601.104 - Outside employment.
(a) Prohibited outside employment. An employee shall not engage in outside employment, either on a paid or unpaid basis, with or for a company or other person whose interests are significantly affected by rates of postage, fees for postal services, the classification of mail, or the operations of the Postal Service.
(b) Prior approval for outside employment. An employee who wishes to engage in outside employment, either on a paid or unpaid basis, shall obtain the prior written approval of the designated agency ethics official. A request for such approval shall be submitted in writing with sufficient description of the employment to enable the designated agency ethics official to give approval based on a determination that the outside employment is not expected to involve conduct prohibited by statute or Federal regulation, including paragraph (a) of this section and 5 CFR part 2635.
(c) Definition of employment. For purposes of this section employment means any form of non-Federal employment or business relationship involving the provision of personal services by the employee. It includes but is not limited to personal services as an officer, director, employee, agent, attorney, consultant, contractor, general partner or trustee. Employment does not include participation in the activities of a nonprofit charitable, religious, professional, social, fraternal, educational, recreational, public service or civic organizations unless such activities involve the practice of a profession within the meaning of 5 CFR 2636.305(b)(1), including the giving of professional advice, or are for compensation other than reimbursement of expenses.