Except as provided in subsection (b) or (c) and in sections 1051, 1081, and 1101 of this title, this subchapter shall apply to any employee benefit plan if it is established or maintained—

(1) by any employer engaged in commerce or in any industry or activity affecting commerce; or

(2) by any employee organization or organizations representing employees engaged in commerce or in any industry or activity affecting commerce; or

(3) by both.

The provisions of this subchapter shall not apply to any employee benefit plan if—

(1) such plan is a governmental plan (as defined in section 1002(32) of this title);

(2) such plan is a church plan (as defined in section 1002(33) of this title) with respect to which no election has been made under section 410(d) of title 26;

(3) such plan is maintained solely for the purpose of complying with applicable workmen’s compensation laws or unemployment compensation or disability insurance laws;

(4) such plan is maintained outside of the United States primarily for the benefit of persons substantially all of whom are nonresident aliens; or

(5) such plan is an excess benefit plan (as defined in section 1002(36) of this title) and is unfunded.

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 [1] (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.

(Pub. L. 93–406, title I, § 4, Sept. 2, 1974, 88 Stat. 839; Pub. L. 101–239, title VII, § 7891(a)(1), Dec. 19, 1989, 103 Stat. 2445; Pub. L. 104–191, title I, § 101(d), Aug. 21, 1996, 110 Stat. 1952; Pub. L. 104–204, title VI, § 603(b)(3)(A), Sept. 26, 1996, 110 Stat. 2938; Pub. L. 107–16, title VI, § 602(b), June 7, 2001, 115 Stat. 96; Pub. L. 107–147, title IV, § 411(i)(2), Mar. 9, 2002, 116 Stat. 47.)