La. Stat. tit. 9 § 3529
The parties in a consumer credit transaction may contract for an additional charge to be assessed against the consumer's account if the consumer tenders a check or makes an electronic debit in payment on such account and such check or electronic debit is returned from any bank, savings and loan association, thrift institution, or credit union or any other organization or institution authorized by the state of Louisiana or the United States to issue checks, drafts, or similar negotiable instruments or payments by electronic means, due to insufficient credit or funds in the account for payment of such 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 not exceed twenty-five dollars or five percent of the amount of the check or electronic payment, whichever is greater. The charge shall be in addition to any delinquency charge assessed under the provisions of R.S. 9:3527. 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.
La. R.S. § 9:3529