A severance agreement is a purchase: the employer buys a release of claims. Two questions decide whether the purchase is effective.
Was there consideration? The payment must be something the employee was not already entitled to. Paying out accrued wages or vacation the employee was owed anyway buys nothing, and a release supported by nothing is worth nothing.
Is the release enforceable as to the claims that matter? Some cannot be waived at all. Claims for unpaid wages are restricted in many states. Unemployment and workers’ compensation rights generally cannot be released. Nothing can stop an employee filing a charge with, or cooperating with, a government agency — though a release of personal monetary recovery on such a charge is often permitted. And releases of age discrimination claims carry specific statutory requirements including consideration and revocation periods that, if missed, void the release of that claim alone while leaving the payment made.
Terms worth attention on both sides: the scope of confidentiality and whether it survives an agency inquiry; non-disparagement and whether it is mutual; references and who gives them; return of property; and continuing obligations under any restrictive covenants, which are often re-affirmed here and are more enforceable for it.
For employees: the deadline in the agreement is usually negotiable, and the first offer usually is too. For employers: an agreement drafted from a template without checking the current statutory requirements is a false economy.