33 USC 914(g)

(g) Notice of payment; penalty. Within sixteen days after final payment of compensation has been made, the employer shall send to the deputy commissioner a notice, in accordance with a form prescribed by the commission [Secretary of Labor], stating that such final payment has been made, the total amount of compensation paid, the name of the employee and of any other person to whom compensation has been paid, the date of the injury or death, and the date to which compensation has been paid. If the employer fails to so notify the deputy commissioner within such time the commission [Secretary of Labor] shall assess against such employer a civil penalty in the amount of $ 100.