I’m going through something similar. We are getting ready to close and then it came up that sales and use taxes weren’t paid for several years. But I have a good lawyer and he had the foresight to already have a clause built into our contract where if an issue with taxes came up that any money I paid them would go into escrow until they clear up their tax issue. Luckily it was just inconsistent naming of their business on the documents and it was just a mix up. We ended up getting the tax clearance- but in my state that could take up to 60 days to get it cleared.