No. Under California law, it's not mandatory for you to sign a severance agreement – regardless of your position, job responsibilities, and the industry you work in. In fact, the law states that a severance agreement is valid only if the parties involved voluntarily enter into it.
Severance is never a requirement of any employer unless you have a signed employment agreement stating otherwise, or, it is a written policy of the company.
It makes no difference how long you've been with a company so yes, it's legal to lay off any and everyone without severance. The exceptions: a union agreement requiring severance, a personal contract calling for a severance. This is usually only for executives and ``key'' people.
Employers are not legally required to offer severance during layoffs, but many choose to do so to maintain goodwill and ease the transition for their former employees. If you are offered a severance agreement, remember that you don't have to sign it right away.
Lack of Voluntary Consent: Under California law, a severance agreement can be considered valid and enforceable only if the parties entered into it voluntarily. If your consent was obtained through coercion, duress, or fraud, the agreement will be deemed invalid.
Present the employee with the severance agreement, worked on by your HR manager, and walk through each section. Leave time for the employee to ask questions and make clear the time frame during which the employee has time to meet with their lawyer, as well as their last day.