Sec. 13-09   Tax roll certified for collection
   After spreading the taxes, the assessor shall certify the tax roll and the mayor shall sign his warrant thereto directing and requiring the treasurer to collect from the several persons named in the tax roll, the several sums mentioned thereon opposite their respective names as a tax or assessment, and granting to him, for the purpose of collecting the taxes, assessments and charges on the roll, all statutory powers and immunities possessed by city treasurers for the collection of taxes.
   Such warrant shall further direct that all taxes paid on or before the 20th day of August shall be collected without additional charge. If any person shall pay one-half of the general city taxes on or before the 31st day of July of the year in which said taxes are assessed, he may pay the remaining one-half of such taxes on or before the 30th day of December of that year without additional charge, but, should the remaining one-half not be paid on or before 30th day of December, then the same shall be subject to collection charges as in section 13-12. Failure to pay the second half on or before December 30th shall subject the property to all the provisions of this charter relating to delinquent taxes the same as if the first half had not been paid, except that no interest or penalty shall be charged against the one-half that is paid. Payment of one-half a tax shall not in any manner nullify the provisions of section 13-12. The persons liable for a tax under the provisions of this charter on July 15 of each year shall be liable for the full amount of the tax, and such tax shall not be considered ‘paid’ until paid in full.