It seems not compulsory. Severance pay is often granted to...

It seems not compulsory.

Severance pay is often granted to employees upon termination of employment. It is usually based on length of employment for which an employee is eligible upon termination. There is no requirement in the Fair Labor Standards Act (FLSA) for severance pay. Severance pay is a matter of agreement between an employer and an employee (or the employee's representative).

https://www.dol.gov/general/topic/wages/severancepay