How to Claim Gambling Losses on Federal Income Taxes

The way that you claim the gambling deduction is relatively simple. First, you have to file Schedule A and itemize your tax deductions. This means that you can't claim the standard deduction, but you can write off expenses like your state income tax, mortgage interest, property taxes, car registration tax and charitable donations. If you have gambling losses, you write them off as "other miscellaneous deductions" on line 28 of Schedule A, where they get combined with your other itemized deductions to reduce your taxable income.

The IRS will only let you deduct losses to the extent that you win. For instance, if you lose $3,000 on one trip to the casino and win $2,100 on another trip in the same year, you can write off $2,100 in losses to offset the $2,100 in winnings, leaving you with a total of $900 of taxable gambling income. If you lost $1,000 on one trip and won $9,500 on another, though, you could claim the entire $1,000 in losses to reduce your net income from gambling to $8,500.

If you claim a gambling loss deduction, you will have to prove that you are entitled to it. Casinos send a form W-2G when you win to let the IRS know that they paid you, but it's up to you to establish your losses. The IRS requires you to keep tickets or receipts and a diary of your winnings and losses to substantiate your deduction. If you can get a printout from the casino of your gambling activity, such as if you use a player's club card, it may be helpful.

The rules for professional gamblers are different. A professional gambler makes a business out of gambling. He can write off his gambling losses and any expenses that he incurs for gambling -- like travel -- to offset gambling income. Since gambling is a business, he would file a Schedule C to report his income and expenses and would also have to pay self-employment taxes on his profits.