If bonds issued by a township under sections 6 to 6c have been sold, the township board of the township may in each year impose a tax upon the taxable property of the township for the purpose of paying the sums of money that become due before the collection of the taxes of the next succeeding year upon the principal of the bonds, or any part of the bonds, and the interest. The tax shall be levied and collected in the same manner as other township taxes are levied and collected.