(1) Upon completion of twenty years of such service and upon retirement, each such member shall receive a pension which, together with an annuity which shall be the actuarial equivalent of his accumulated contributions at the time of his retirement and an additional pension which is the actuarial equivalent of the reserve-for-increased-take-home-pay to which he may then be entitled shall be sufficient to provide him with a retirement allowance equal to one-half of his final average salary.

(2) Upon attainment of the mandatory retirement age and upon retirement without completion of twenty years of such service, each such member shall receive a pension which together with an annuity which shall be the actuarial equivalent of his accumulated contributions at the time of his retirement and an additional pension which is the actuarial equivalent of the reserve-for-increased-take-home-pay to which he may then be entitled, shall be sufficient to provide him with a retirement allowance equal to one-fortieth of his final average salary for each year of creditable service. Only for the purpose of determining the amount of the pension provided in this subdivision, the annuity shall be computed as it would be if it were not reduced by the actuarial equivalent of any outstanding loan, and if it were not increased by the actuarial equivalent of any additional contributions or contributions pursuant to waiver under subdivision j of section twenty-one of this article, and if it were not reduced by reason of the members election to decrease his annuity contributions to the retirement system in order to apply the amount of such reduction in payment of his contributions for old-age and survivors insurance coverage. g. The increased pensions to members of the police force, together with all other expenses of this retirement plan exceeding the contribution required to be made by members pursuant to subdivision d of this section, shall be paid from contributions made by the county on account of such members. The actuary of the retirement system shall compute the additional contribution for each member who participates under this section. Such additional contributions shall be computed on the basis of contributions during the prospective service of such member which will cover the liability of the retirement system for such extra pensions. Upon approval by the comptroller, such additional contributions shall be certified by him to the county executive of the county. The amount thereof shall be included in the annual appropriation of the county for the Nassau county police. Such amount shall be paid on the warrant of the county comptroller to the pension accumulation fund of the retirement system. h. Every member of the police force except the commissioner of police contributing under this section shall leave the service on the last day of the calendar month in which he attains age fifty-nine, which shall be his mandatory retirement age. The commissioner after age fifty-nine and before age seventy may elect to retire and if he does so the date of his retirement shall for the purpose of this section be deemed his mandatory retirement age. i. The provisions of this section shall be controlling notwithstanding any provision in this article to the contrary.