Nobody answered this, but I did a lot of research on my own and figured it was worth listing what I found.Basically throughout the year youu2019re expected to keep a hand written log of all your cash game sessions with wins and losses. That includes the date, place you played, start time, end time, amount won/lost, table number, and whoever accompanied you. Most filers donu2019t have all that information, but do a best effort. Data in apps/spreadsheets isnu2019t considered valid for some reason so you can transcribe it.As a recreational gambler, you report all of your gross winnings as income, and claim all your losses as a deduction. For example if I won $20k and lost $12k then I donu2019t report the net $8k as income. I report $20k as income, and claim $12k as a deductions in gambling.If youu2019re using the Standard Deduction you can get really screwed by this as you need $12k in deductions before any of your losses count against your gross income.For poker tournaments always get a receipt if you plan to report not cashing as a loss. Most major tournaments print one out.Professional gamblers can claim net winnings as income, as well as expenses going to and from tournaments and so forth. But the bar for being a professional gambler is pretty high, includes being a net winner, play regular work like hours at high volume, have a clear profit motive in playing and not for enjoyment, separate bank accounts for poker money and so forth are useful too. The vast majority of poker players are going to be considered recreational.Other miscellaneous notes:Cash transactions that over $10k at casinos are reported to the IRS.Large wins (saying from winning a poker tournament) are reportedly separately in a W2G from the 1099-MISC income. The casino will fill that out and file it with the IRS, and give you a copy, and you need to file that as well.