(a) It shall be the duty of the board of public education, or the collector if designated by the Board, to sue for the recovery of all taxes due, not paid when due. Such suits shall be begun within one (1) year after such taxes have been assessed.

(b) If for any reason the tax is not paid when due in each year, interest at the rate of six per centum (6%) per annum or at a per annum rate which does not exceed the Federal Reserve Discount Rate in effect for Federal Reserve District Four on December 1 of the preceding tax year, whichever is greater, on the amount of said tax, and an additional penalty of one-half of one per centum ( ½ %) of the amount of the unpaid tax for each month, or fraction thereof, during which the tax remains unpaid, shall be added and collected: Provided, That the maximum penalty which shall be imposed on a tax not paid when due shall be seven (7%) percent. A school district shall, on or before December 31, establish by resolution the specific per annum interest rate to be imposed on unpaid taxes during the following tax year. Where suit is brought for the recovery of any such tax the person shall be liable for, and in addition to the tax assessed against such person, the costs of such collection, and the interest and penalties herein imposed shall be collected.

(c) All penalty in excess of one-half of one per centum ( ½ %) per month on unpaid taxes levied pursuant to the act for the year 1955 and all previous years are hereby abated, if the unpaid taxes and penalty (not to exceed one-half of one per centum ( ½ %) per month) and interest are paid on or before December thirty-one, one thousand nine hundred fifty-six, provided the taxpayer's 1955 and 1956 taxes levied under this act are paid. No refund of taxes, interest or penalties paid prior to the date of the enactment of this act shall be made as a result of the amendments herein contained.