Hi, and thank you for writing. Not sure if you are the seller or buyer here, so I'll go over both. If the sales contract says that the buyer can kill the deal if the appraisal is low, he or she can do that. If the buyer is financing with a government-backed mortgage, that clause becomes part of your agreement by law. The seller cannot force the buyer to go through with it. In addition, if the buyer has a conventional (non-government) loan, chances are good that the lender's approval depends on the property meeting its guidelines, including an appraised value. So a low appraisal is also an easy out for the buyer. The buyer can, if he or she chooses, make a higher down payment and close the deal. Few will do this unless they believe the appraisal was badly done or want the house very badly, and also have the means to pay more. In most cases, the parties re-negotiate the sales price or kill the deal.