The adjustment to fair market value comes after you finish entering all your 1099-MISC forms. After you enter a 1099-MISC it asks you if you have another one. If you select No, the next screen is the 1099-MISC Summary. When you click Done on the 1099-MISC Summary screen, you get the Fair Market Value screen. If you are not getting it, check your entries for the 1099-MISC. Is the prize amount in box 3? Did you select "This was prize winnings" on the screen that asks about "uncommon situations"?