If a pension plan allows an employee to elect to make voluntary employee contributions to accounts and annuities as provided in section
408
(q) of title
26, such accounts and annuities (and contributions thereto) shall not be treated as part of such plan (or as a separate pension plan) for purposes of any provision of this subchapter other than section
1103
(c),
1104, or
1105 of this title (relating to exclusive benefit, and fiduciary and co-fiduciary responsibilities) and part 5 of subtitle B of this subchapter (relating to administration and enforcement). Such provisions shall apply to such accounts and annuities in a manner similar to their application to a simplified employee pension under section
408
(k) of title
26.