Am I liable if the seller times a termination the day before closing specifically to avoid passing the cost to me?

In a properly structured asset purchase, generally no — a termination carried out by the seller before closing, however it was timed, is legally the seller's act as the employer at that point, and the resulting severance or termination pay obligation is theirs to cover, not yours, provided your purchase agreement is clear that pre-closing employee liabilities stay with the seller.

That said, a termination suspiciously timed right before closing is worth flagging during due diligence rather than treated as routine, both because it can signal the seller is trying to manage costs at your expense in other ways too, and because it's worth confirming the termination was actually properly handled and paid out, since an improperly handled termination just before a sale can sometimes generate a claim that surfaces later regardless of who's technically liable for it.

In a share purchase, by contrast, timing matters less to your exposure, since you'll own the corporation either way and any unpaid severance from a pre-closing termination continues with it. Review termination timing and payout status carefully as part of employee due diligence in either structure. A Treadstone business lawyer can help assess this.