According to the IRS and from the website here:
https://turbotax.intuit.com/tax-tools/tax-tips/Taxes-101/Can-You-Claim-Gambling-Losses-on-Your-Taxes...
The IRS requires you to keep a diary of your winnings and losses as a prerequisite to deducting losses from your winnings. This includes:
- lotteries
- raffles
- horse and dog races
- casino games
- poker games
- and sports betting
Your diary must include:
- the date and type of gambling you engage in
- the name and address of the places where you gamble
- the people you gambled with
- and the amount you win and lose
Other documentation to prove your losses can include:
- Form W-2G
- Form 5754
- wagering tickets
- canceled checks or credit records
- and receipts from the gambling facility
