Start by looking at Form 1040, as VolvoGirl suggested. The amount you owe is on line 37 at the bottom of page 2. Look above that, on lines 16 through 23 to see where the amount is coming from. If it's coming from Schedule 2 or Schedule 3, look at that schedule. If it's tax on line 16, look at lines 1 through 8 on page 1 to see what income is entered.
