La. Stat. tit. 33 § 3307
Municipalities complying with the provisions of this Sub-part may issue, execute, negotiate, sell, and deliver negotiable interest bearing coupon certificates of the municipality in an amount not exceeding the total amount of the installments or deferred payments as provided for in R.S. 33:3306, the certificates to bear interest not exceeding six per centum per annum payable annually and maturing serially over a period not exceeding twenty years. In no event shall the certificates extend over a longer period of time than that provided for by the ordinance levying the local or special assessments which may be payable in annual installments. The certificates shall be of such form, date, denomination, and payable in principal and interest at such time and place as the governing authority may determine; the certificates shall be secured by and paid from, in principal and interest, the irrevocable pledge and dedication of the funds derived from the levy and collection of the special assessments on the real property abutting the improvements and shall be payable in annual installments or deferred payments as provided for by this Sub-part, which funds shall be set aside in a separate fund and shall not be drawn upon for any other purpose than to pay the principal and interest of the certificates.
La. R.S. § 33:3307