sales cont expired. seller has IRS lien to be paid and being delayed.

I will assume that the contract has not simply expired by its terms, but that the seller has breached the contract by not performing within a given time period.  I will also assume that the IRS only has a lien, and not a garnishment, order of attachment, or injunction against transfer. While the IRS lien may not prevent you from obtaining specific performance, you might not want it if the IRS has a lien on that asset.  For example, if the IRS has a lien on the seller's inventory, with no injunction or attachment, the asset can be sold, but the sale is still subject to the lien, so that the IRS could theoreticall foreclose on that asset to satisfy its lien, even if the asset has been transferred to you.  Moreover, you will have a very hard time selling the asset yourself. Also, you can't win specific performance unless the thing being sold is unique in some way, i.e. can't be purchased elsewhere.  Real property is unique.  A Renoir painting is unique.  Two pairs of black socks are not unique.  The buyer's remedy when the seller breaches a contract to sell non-unique goods is to buy the same goods from someone else and sue the seller for the extra money he/she had to pay.  If you can prove what it would have cost to replace the goods, you don't have to actually go out and buy replacements if you don't want, but just sue the seller for the difference between the contract price you were going to pay, and the actual market price if you had replaced the goods.  Alternatively, you may be able to rescind the contract, meaning you would get back the money you had already paid the seller (although the IRS may have priority.)