got a lot of DMs asking this so let me just put it here.
quick context: i've been through two layoffs, one as an IC and one as a staff eng. negotiated both times. it takes less time than you think and people give up too early.
the actual timeline: day 1 - you get the packet. you're supposed to sign within X days (varies, usually 21 for over-40 workers under OWBPA, sometimes shorter for younger workers). this is your window.
day 2 or 3 - you send a short, professional email to HR asking to speak. not asking for more money yet. just opening a channel.
day 4-6 - call happens. you ask your questions: what's the basis for the package, is this standard across the org, is there flexibility on equity vesting. you listen more than you talk.
day 7-10 - you come back with a specific, narrow ask. don't ask for everything. pick two things: maybe an extra week of pay and continued vesting for 30 days. the more specific the ask, the easier it is for HR to say yes.
total elapsed time: 1-2 weeks. you still sign before the deadline.
what actually works: the single most effective thing i've done is mention my unvested equity and ask directly if the company would consider an accelerated cliff. this is something they can say yes to without reopening the whole comp structure. my first layoff they added 3 months of vesting. second one they didn't, but they extended my healthcare through end of quarter, which was worth more at that point.
when to stop: if they've said no twice to a specific ask, it's over. don't renegotiate the thing they already said no to.
one caveat: this gets more complicated if there's any dispute about the termination itself. that's a different conversation and probably involves a lawyer. i'm talking about clean, no-fault RIF situations.