The following words and phrases when used in this chapter shall have the meanings given to them in this section unless the context clearly indicates otherwise:

“Actuarially required contribution rate.” The employer contribution rate as calculated pursuant to section 5508(a), (b), (c), (e) and (f) (relating to actuarial cost method).

“Costs added by legislation.” The sum, if positive, of all changes in the actuarially required contribution rate resulting from legislation enacted in the year since the last actuarial valuation and not included in the determination of the prior year's final contribution rate, computed as the rate of total compensation of all active members certified by the actuary as sufficient to make the employer normal contributions and sufficient to amortize legislatively created changes in the unfunded actuarial liability in equal dollar annual installments over a period of ten years from the July 1 following the valuation date.