For tax years 2018 through 2025, gambling losses and expenses are limited to the amount of gambling winnings[1].
Starting in tax years after 2025, the deduction for gambling losses will be further limited to 90% of such losses incurred during the year, while still being capped at the amount of gambling gains for the year[2].
For both casual and professional gamblers, accurate records must be maintained to substantiate losses and winnings[3].
Spouses filing jointly can combine their gambling losses to the extent of their combined gambling gains[1, 3].