; (B) except as provided in subparagraph (C), may continue to serve after the expiration of the fixed term of office of the commissioner that the person succeeds until a successor is appointed and has been confirmed and taken the oath of office; and (C) may not continue to serve after the expiration of the session of Congress that begins after the expiration of the fixed term of office of the commissioner that the person succeeds. (3) Effect of vacancy on powers of Commission Except as provided in section 9(e) (relating to repeal of prior rules), no vacancy in the Commission shall impair the right of the remaining commissioners to exercise all the powers of the Commission. (d) Salary of Commissioners (1) In general Each Commissioner shall receive an annual salary at the annual rate payable from time to time for grade 16 of the pay scale of the Securities and Exchange Commission, payable in monthly installments. (2) Chair The Chair of the Commission, during the period of service as Chair, shall receive an annual salary at the annual rate payable from time to time for grade 17 of the pay scale of the Securities and Exchange Commission. (e) Principal office (1) General sessions The principal office of the Commission shall be in the District of Columbia, where its general sessions shall be held. (2) Special sessions Whenever the convenience of the public or of the parties may be promoted or delay or expense prevented thereby, the Commission may hold special sessions in any part of the United States. (f) Employees (1) In general The Commission may, subject to the civil service laws and the Classification Act of 1949, as amended, appoint such officers, engineers, accountants, attorneys, inspectors, examiners, and other employees as are necessary in the exercise of its functions. (2) Assistants (A) Professional assistants