I used to work somewhere and was laid off with a month of severance that should've ended 2 weeks ago. I still have the company payment app on my phone because I need it to get my W-2. A notification popped up that I received a check this week. Weirdly enough, the check was higher than my normal pay because it accounted for the fact that my benefits are no longer being taken out.

I know I need to keep this money in a savings account and not touch it for X amount of time because they might demand it back. But is there an expiry date on when they can ask for it back? If I keep getting future checks, am I legally required to notify them, or can I keep setting the money aside and not saying anything?

Also, can they pull it directly out of my bank account? I'd rather move the money into a separate account where I'm guaranteed not to touch it but don't want to risk an overdraft fee if they can rip it right back out of the account.

Company is super disorganized so I have no idea how long it will take before they notice, or if they'll notice at all if this was just a one-off mistake.