My uncle bought an account receivable with a face value of $100,000 for $72,000. They just informed my uncle that he could not expect to collect more than 80 cents on the dollar with respect to the receivable. What is the maximum amount of the bad debt deductin for my uncle for the current year?

If he gets them at 72 cents on the dollar and cannot collect more than 80, I don't see there is any bad debt for him unless he sells them for less than 72 cents. He will have a profit once they are sold more than 72 cents on the dollar.