La. R.S. 6:969.17

The parties in a motor vehicle credit transaction may contract for an additional charge to be assessed if the consumer tenders a check in payment or a payment by electronic means and such check or electronic payment is returned from any bank, savings and loan association, thrift institution, credit union, or any other organization or institution authorized to issue checks, drafts, or similar negotiable instruments or electronic payments, due to insufficient credit or funds in the account for payment of the check or electronic payment in full upon its presentation, or due to account closure, stop payment, drawn on uncollected funds, or any other reason for which the instrument or electronic payment is not paid. The additional charge shall be five percent of the amount of the check or electronic payment, but in no case shall this charge exceed fifteen dollars. The charge shall be in addition to any delinquency charge assessed under the provisions of R.S. 6:969.15. For the purposes of this Section, the phrase "due to insufficient credit or funds" means a check or electronic payment returned unpaid for any reason.