(a) Except as provided in subdivision (c), in any county or district subject to the provisions of Section 31676.1, 31676.11, 31676.13, or 31676.14, the retirement allowance payable for retirement service rendered prior to the effective date of the resolution mentioned in Section 31800 shall be computed in accordance with the provisions of Section 31676.1, 31676.11, 31676.13, or 31676.14, whichever is applicable. Except as provided in subdivision (b), the retirement allowance with respect to service performed after May 31, 1957, shall equal the total of the following:

1. (1) The fraction of one-ninetieth of the first three hundred fifty dollars ($350) monthly of the member’s final compensation set forth in the table appearing in Section 31676.1, 31676.11, 31676.13, or 31676.14, whichever is applicable, in the column applicable to the member’s age at retirement taken to the preceding completed quarter year multiplied by the number of years of creditable service as provided therein.
2. (2) The fraction of one-sixtieth of any remaining portion of the member’s final compensation set forth in the table appearing in Section 31676.1, 31676.11, 31676.13, or 31676.14, whichever is applicable, in the column applicable to the member’s age at retirement taken to the preceding completed quarter year multiplied by the number of years of creditable service.

(b) With respect to persons who become members of a county retirement system after the effective date of the amendments to this section enacted at the 1979–80 Regular Session, the retirement allowance shall equal the following:

1. (1) The fraction of one-ninetieth of the first one thousand fifty dollars ($1,050) monthly of the member’s final compensation set forth in the table appearing in Section 31676.1, 31676.11, 31676.13, or 31676.14, whichever is applicable, in the column applicable to the member’s age at retirement taken to the preceding completed quarter year multiplied by the number of years of creditable service as provided therein.
2. (2) The fraction of one-sixtieth of any remaining portion of the member’s final compensation set forth in the table appearing in Section 31676.1, 31676.11, 31676.13, or 31676.14, whichever is applicable, in the column applicable to the member’s age at retirement taken to the preceding completed quarter year multiplied by the number of years of creditable service.
3. (3) This subdivision may be made applicable in any county of over six million population on the first day of the month after the board of supervisors of such county adopts by majority vote a resolution providing that this subdivision shall become applicable in such county.