La. Stat. tit. 33 § 3391
In order to meet the payments due to the contractor in the amounts represented by deferred payments as provided for in this Sub-part the municipality may issue and sell after due advertisement for not less than fifteen days paving certificates in an amount not exceeding the total of the deferred payments authorized herein. The certificates when issued shall be direct obligations of the municipality secured in principal and interest by the deferred payments due and owing by the several property owners, which deferred payments shall constitute a special fund for this purpose only. The paving certificates shall bear interest at a rate not exceeding six per cent per annum payable annually and shall mature in not more than fifteen annual installments of approximately even amounts and may be called for payment in whole or in part at any interest payment period.
La. R.S. § 33:3391