The township board of directors shall, annually, not less than twenty nor more than sixty days prior to the first day of September, make out and file with the clerk of the county commission of their county an estimate of the amount of money required to defray the expenses of said township during the next ensuing year. Said estimates shall be signed by the president and attested by the clerk of the board. The clerk of the county commission shall cause the same to be placed on the tax books of said township; provided that the amount of such expenses shall not exceed in any one year twenty cents on the hundred dollars assessed valuation of the taxable property within said township.