Am I liable for severance owed to someone the seller fired right before closing?

If the deal is structured as an asset purchase, generally no — a termination that happened before closing, and any severance it triggered, is a liability of the selling corporation at the time it occurred, and a properly drafted asset purchase agreement should confirm you aren't assuming pre-closing employee liabilities like this one.

If the deal is a share purchase, the answer is different, because you're acquiring the same corporate employer that did the firing, and any severance obligation that arose before closing but wasn't actually paid is a debt that continues to sit with that corporation — meaning, practically, with you as its new owner.

Either way, this is exactly the kind of scenario worth specifically checking for in due diligence, since a termination timed right before closing can sometimes reflect an attempt to shift a cost, or simply ordinary business timing that happened to land close to your deal. Confirm whether severance was actually paid, and if not, make sure your purchase agreement and any price adjustment or holdback account for it. A Treadstone business lawyer can help review recent terminations as part of your employee due diligence.