In all cities coming under the provisions of this act there shall be levied annually at the time for the levying of taxes for city purposes, for the purpose of paying such pensions and to pay a portion of the principal and interest on bonds issued by such city under the authority of Kan. Stat. Ann. § 12-1774, and amendments thereto, a tax on all tangible taxable property within the limits of the city. In lieu of levying the tax authorized in this section, payments to the city’s employees’ pension fund may be made from moneys in any employee benefits contribution fund established pursuant to Kan. Stat. Ann. § 12-16,102.