The special assessment tax shall be levied, computed, entered, collected and enforced at the same time, in the same manner, by the same persons and with the same penalties as other taxes for city purposes and when collected shall be paid into the city treasury to the credit of the fund of the district and shall, subject to the provisions of Sections 18092 and 18092.1, which shall be applicable to the procedure provided by this chapter, be used only for the payment of the expenses of the district.