Suppose you’re an Oklahoma resident and enjoy gambling one of the many casinos in the Sooner State. You have $100,000 of gambling winnings and $100,000 of gambling losses. You itemize on your federal return anyway (you have mortgage interest, state taxes, and charitable donations), and the wash is just fine. On your Oklahoma return, you’re surprised to find your Oklahoma charitable donations are limited to $17,000 (plus the amount of medical and charitable donations).
Yes, Oklahoma has joined the states that are bad for gamblers. In my hypothetical, an amateur gambler would pay tax on $83,000 of phantom income. This change is the result of a law passed in April 2018.