Employment attorney here with a common misconception to address: California does not require employers to pay severance. There is no statutory right to severance pay under California law or the FLSA. Severance is purely a matter of contract, company policy, or negotiation.
That said, there are several situations where severance becomes effectively mandatory or at least strongly incentivized. If the company has a written severance policy in its employee handbook, that policy can become an enforceable contract under California law. If the employer promised severance verbally or in an offer letter, that promise may be enforceable under promissory estoppel or as an implied contract. And for mass layoffs, the California WARN Act (Labor Code Sections 1400-1408) requires 60 days notice or 60 days pay in lieu of notice for plant closings or mass layoffs affecting 50 or more employees.
The most important thing to understand about severance agreements is that they are a negotiation, and the employer is almost always getting something valuable in return -- typically a release of all legal claims. Before you sign a severance agreement, evaluate what claims you might be giving up. If you have potential claims for discrimination, harassment, retaliation, unpaid wages, or FMLA violations, your leverage in negotiating a higher severance amount increases significantly.
For employees over 40, the Older Workers Benefit Protection Act (OWBPA, 29 USC Section 626(f)) requires that severance agreements include specific language, give you at least 21 days to consider the agreement (45 days for group layoffs), and provide a 7-day revocation period after signing. If the agreement does not comply with OWBPA, the release of age discrimination claims is invalid -- which is a common employer mistake.
My standard advice: never sign a severance agreement on the spot. Take the full consideration period, have an employment attorney review it (many will review a severance agreement for a flat fee of 500-1,000 dollars), and negotiate. I have seen initial severance offers doubled or tripled through informed negotiation, particularly when the employee has potential legal claims the employer wants released.