All payments provided for members under Section 8.568 shall be made from funds derived from the following sources, plus interest earned on said funds:
(a) The normal rate of contribution of each member under this section shall be based on his age taken to the next lower complete quarter year, (1) at the earlier of the dates he became a member under Section 8.507, 8.509 or 8.567, in the case of persons who are members under these sections, or (2) on his age at the date he becomes a member under Section 8.568 in the case of persons who become members on or after July 1, 1949, without credit for service counted under Section 8.578. The age of entrance into the fire department shall be determined by deducting the member's service credited under Section 8.578 as rendered prior to the date upon which his age is based for determination of his rate of contribution according to the sentence next preceding, from said age. The normal rate of contribution of each such member, to be effective from the effective date of membership under Section 8.568, shall be such as, on the average for such member, will provide, assuming service without interruption, under Section 8.570, one-third of that portion of the service retirement allowance to which he would be entitled, without continuance to dependents, upon first qualifying as to age and service, for retirement under that section, which is based on service rendered after the date upon which his age is based for determination of his rate of contribution according to the first sentence in this paragraph, and assuming the contribution to be made from that date. The normal rate of contribution, however, shall not exceed six percent.
(b) The dependent contributions of each member under this section which shall be required of each member throughout his membership in addition to the normal contributions, and in the same manner as normal contributions, shall be such as, on the average for such member, will provide, assuming service without interruption under Section 8.570, and upon his first qualifying as to age and service for retirement under that section, one-third of the portion of his allowance, which is to be continued under Section 8.573 after his death and throughout the life of a surviving wife whose age at said death is three years less than the age of said member. If, at the date of retirement for service or retirement for disability resulting from injury received in performance of duty, said member has no wife who would qualify for the continuance of the allowance to her after the death of said member, or upon retirement for disability resulting from other causes, regardless of his marital condition, the dependent contributions with accumulated interest thereon, shall be paid to him forthwith. The dependent rate of contribution, however, shall not exceed the difference between six percent and the member's normal rate of contributions, and said dependent rate may be taken as a flat percentage of the member's normal rate, regardless of the age of qualification for service retirement.
(c) There shall be deducted from each payment of compensation made to a member under this section, a sum determined by applying the member's rates of contribution to such compensation payment. The sum so deducted shall be paid forthwith to the Retirement System. Said contribution shall be credited to the individual account of the member from whose salary it was deducted, and the total of said contributions, together with interest credited thereon in the same manner as is prescribed by the Board of Supervisors for crediting interest to contributions of other members of the Retirement System, shall be applied to provide part of the retirement allowance granted to, or allowance granted on account of said member, or shall be paid to said member or his estate or beneficiary as provided in Sections 8.576, 8.577 and 8.578.
(d) Contributions based on time included in Subsections (a), (b) and (c) of Section 8.578, and deducted prior to July 1, 1949, from compensation of persons who become members under Section 8.568, and standing with interest thereon, to the credit of such members on the records of the Retirement System on said date, shall continue to be credited to the individual accounts of said members and shall be combined with and administered in the same manner as the contributions deducted after said date.
(e) The total contributions, with interest thereon, made by or charged against the City and County and standing to its credit, in the accounts of the Retirement System, on account of persons who become members under Section 8.568, shall be applied to provide the benefits under said section.
(f) The City and County shall contribute to the Retirement System such amounts as may be necessary, when added to the contributions referred to in the preceding paragraphs of this Section 8.579, to provide the benefits payable under this section. Such contributions of the City and County to provide the portion of the benefits hereunder which shall be based on service rendered by each member prior to the date upon which his age is based for determination of his rate of contribution in Subsection (a) Section 8.579, shall not be less during any fiscal year than the amount of such benefits paid during said year. Such contributions of the City and County to provide the portion of the benefits hereunder which shall be based on service rendered by respective members on and after the date stated in the next preceding sentence, shall be made in annual installments, and the installment to be paid in any year shall be determined by the application of a percentage to the total compensation paid during said year, to persons who are members under Section 8.568, said percentage to be the ratio of the value on July 1, 1949, or at the later date of a periodical actuarial valuation and investigation into the experience under the system, of the benefits thereafter to be paid under this section, from contributions of the City and County, less the amount of such contributions, and plus accumulated interest thereon, then held by said systems to provide said benefits on account of service rendered by respective members after the date stated in the sentence next preceding, to the value of said respective dates of salaries thereafter payable to said members. Said values shall be determined by the actuary, who shall take into account the interest which shall be earned on said contributions, the compensation experience of members, and the probabilities of separation by all causes, of members from service before retirement and of death after retirement. Said percentage shall be changed only on the basis of said periodical actuarial valuation and investigation into the experience under the system. Said actuarial valuation shall be made every even-numbered year and said investigation into the experience under the system shall be every odd-numbered year.
(g) To promote the stability of the Retirement System through a joint participation in the result of variations in the experience under mortality, investment and other contingencies the contributions of both members and the City and County held by the system to provide the benefits under this section, shall be a part of the fund in which all other assets of said system are included. Nothing in this section shall affect the obligations of the City and County to pay to the Retirement System any amounts which may or shall become due under the provisions of the Charter prior to July 1, 1949, and which are represented on said effective date, in the accounts of said system by debits against the City and County.