(1) Purpose. The rules adopted in this chapter further define and clarify the application of the portability statutes, chapter 41.54 RCW. Chapter 41.54 RCW allows:

(a) Service in dual member systems to be combined to determine service retirement eligibility; and

(b) Compensation earned in one dual member system to be used to calculate a retirement allowance in another designated system.

(2) Scope. This chapter shall apply to the retirement systems listed in RCW 41.50.030, except for LEOFF Plan 1. This chapter must be read to be consistent with the statutory provisions of chapter 41.54 RCW and the statutory provisions governing the dual member systems. These rules may be used by the first class city retirement systems but do not mandatorily apply to them. These rules do apply to all dual member benefits calculated and paid by the department, even if one of the member's systems is a first class city retirement system.