Gambling winnings are taxable in Iowa even if the winner is not an Iowa resident. Nonresidents should complete the IA 1040, showing income from all sources, including Iowa gambling winnings, lines 1 through 12.
Then use the IA 126 to determine your credit based upon the percentage of Iowa income to total income.
This credit should be entered on IA 1040, line 13, then complete the remainder of the return.
Include a copy of your federal return.