Each member of the Board shall serve on a full-time basis, and may not, concurrent with service on the Board, be employed by any other person or engage in any other professional or business activity. No member of the Board may share in any of the profits of, or receive payments from, a public accounting firm (or any other person, as determined by rule of the Commission), other than fixed continuing payments, subject to such conditions as the Commission may impose, under standard arrangements for the retirement of members of public accounting firms.