(

a) Persons who are members of any other retirement or pension system supported wholly or in part by funds of the United States government, any state government, or any political subdivision thereof and who are receiving credit in the other system for service are, as to that service, excluded from this system. (b)

(1) For the purpose of this

section only, persons who are receiving pensions, retirement allowances, or other payments, from any source whatever, because of service rendered to an employer other than the state and while they were not in state service, are not, because of that receipt, members of any other retirement or pension system.

(2) For the purposes of this

section only, persons who participate in a deferred compensation plan established pursuant to

Chapter 4 (commencing with

Section 19993) or

Chapter 8.6 (commencing with

Section 19999.3) of

Part 2.6 or pursuant to

Article 1.1 (commencing with

Section 53212) of

Chapter of Part of Division of Title 5, are not, because of that participation, members of any other retirement or pension system.

(3) For the purposes of this

section only, persons who participate in a money purchase pension plan and trust that meets the requirements of

Section 401(

a) of Title of the United States Code are not, because of that participation, members of any other retirement or pension system, so long as the contracting agency has received a ruling from the Internal Revenue Service stating that the money purchase pension plan and trust qualifies under

Section 401(

a) and furnishes proof thereof upon request by the board.

(4) For the purposes of this

section only, persons who participate in a supplemental defined benefit plan maintained by their employer that meets the requirements of

Section 401(

a) of Title of the United States Code are not, because of that participation, members of another retirement or pension system, provided that all of the following conditions exist: (

A) The defined benefit plan provided under this part has been designated as the employer’s primary plan for the person. (

B) The supplemental defined benefit plan has received a ruling from the Internal Revenue Service stating that the plan qualifies under

Section 401(

a) of Title of the United States Code, and has furnished proof thereof to the employer and, upon request, to the board. (

C) The person’s participation in the supplemental defined benefit plan does not, in any way, interfere with the person’s rights to membership in the defined benefit plan, or any benefit provided, under this part.

(5) For purposes of this

section only, a person who elects membership pursuant to

Section is deemed, with respect to service with the California National Guard, not to be a member of any other retirement or pension system.