How to prove gambling losses or winnings for tax deduction?

godfather: How do you prove gambling losses or winnings for tax deduction purposes?
How do you get documentation showing your losses or winnings for tax purposes? Like for blackjack? Or slots? Or sportsbetting? Gambling losses or tax deductible right? (Against your gambling winnings as I understand it) Any info would help. Thanks

Answers and Views:

Answer by K
if you lose in gambling, there’s no tax deduction

but if you win a lot, like 5 grams or more, then casino will give you something like an invoice then you need to report the invoice when you prepare for your taxes next time.

Answer by steamer
If you get rated whenever you play, the casino will give you a printout of your wins & loses to the penny. You would have to have lost alot to get a good deduction, before winning. You can’t deduct any thing unless you win enough to fill out W2-G form.