Those members subject to this chapter who became disabled in the line of duty and who received or are receiving benefits under Title 51 RCW or a similar federal workers' compensation program shall receive or continue to receive service credit subject to the following:

(1) No member may receive more than one month's service credit in a calendar month.

(2) No service credit under this section may be allowed after a member separates or is separated without leave of absence.

(3) Employer contributions shall be paid by the employer at the rate in effect for the period of the service credited.

(4) Employee contributions shall be collected by the employer and paid to the department at the rate in effect for the period of service credited.

(5) Contributions shall be based on the regular compensation which the member would have received had the disability not occurred. If contribution payments are made retroactively, interest shall be charged at the rate set by the director on both employee and employer contributions. No service credit shall be granted until the employee contribution has been paid.

(6) The service and compensation credit shall not be granted for a period to exceed twenty-four consecutive months.

(7) Should the legislature revoke the service credit authorized under this section or repeal this section, no affected employee is entitled to receive the credit as a matter of contractual right.