Rule XXXVIII of the Standing Rules of the United States Senate, established by the Senate Committee on Rules and Administration, governs the prohibition of unofficial office accounts.
Text of Rule XXXVIII 
- (a) No Member may maintain or have maintained for his use an unofficial office account. The term "unofficial office account" means an account or repository into which funds are received for the purpose, at least in part, of defraying otherwise unreimbursed expenses allowable in connection with the operation of a Member's office. An unofficial office account does not include, and expenses incurred by a Member in connection with his official duties shall be defrayed only from
- 1. personal funds of the Member;
- 2. official funds specifically appropriated for that purpose;
- 3. funds derived from a political committee (as defined in section 301(d) of the Federal Election Campaign Act of 1971 (2 U.S.C. 431)); and
- 4. funds received as reasonable reimbursements for expenses incurred by a Member in connection with personal services provided by the Member to the organization making the reimbursement.
- (b) Notwithstanding subparagraph (a), official expenses may be defrayed only as provided by subsections (d) and (i) of section 311 of the Legislative Appropriations Act, 1991 (Pub. L. 101-520).
- (c)For purposes of reimbursement under this rule, fair market value of a flight on an aircraft shall be determined as provided in paragraph 1(c)(1)(C) of rule XXXV.
- 2. No contribution (as defined in section 301(e) of the Federal Election Campaign Act of 1971 (2 U.S.C. 431)) shall be converted to the personal use of any Member or any former Member. For the purposes of this rule "personal use" does not include reimbursement of expenses incurred by a Member in connection with his official duties.
External links 
Standing Rules of the United States Senate