Mandatory allotments. An agency must permit an employee to make—

An allotment for dues to a labor organization under section 7115 of Title 5, United States Code;

An allotment for dues to an association of management officials and/or supervisors under § 550.331;

An allotment for charitable contributions to a Combined Federal Campaign under § 550.341;

An allotment for income tax withholding under § 550.351;

Two or more allotments to an employee's personal account(s) at a financial organization;

An allotment for child support and/or alimony payments under § 550.361; and

Any allotment effecting a salary reduction as part of a flexible benefits plan established by the Office of Personnel Management in conformance with section 125 of title 26, United States Code.

Discretionary allotments. In addition to those allotments provided for in paragraph (a) of this section, an agency may permit an employee to make an allotment for any legal purpose deemed appropriate by the head of the agency (or designee). This paragraph does not constitute an independent authority for an agency to permit pretax allotments in addition to those authorized by the Office of Personnel Management as described in paragraph (a)(7) of this section.

The head of an agency may prescribe such additional regulations governing allotments as appropriate which are consistent with subchapter III of chapter 55 of title 5, United States Code, and this subpart. Discretionary allotments under this subpart may be limited in number as determined appropriate by the head of the agency.