How Does the IRS Define a Professional Gambler?

The IRS treats you as a professional gambler when your wagering rises to the level of a trade or business, meaning you pursue it full-time, in good faith, with regularity, and as a genuine source of livelihood. That standard comes from the Supreme Court’s 1987 decision in Commissioner v. Groetzinger, and every audit and Tax Court case on gambler status since has turned on it.¹ The classification matters because it unlocks Schedule C reporting and ordinary business deductions, but claiming it without meeting the standard can trigger a 20% accuracy-related penalty on top of the recalculated tax.²

The Groetzinger Standard

There is no checkbox on a tax form that turns you into a professional gambler. The definition comes from case law. Groetzinger involved a full-time dog track bettor who wagered only on his own account, and the Supreme Court held that a gambler in that position is engaged in a trade or business when the activity is pursued full-time, in good faith, with regularity, and for the production of income as a livelihood.¹ The Court specifically pointed to “constant and large-scale effort” paired with applied skill as what separated the taxpayer’s work from a hobby or an occasional bet for amusement.

Two implications follow from that language. If you gamble part-time while holding another full-time job, you face an uphill battle. And if you cannot point to skill-based play with a genuine expectation of profit, sporadic casino trips will not qualify no matter how much money moves across the table.

The Nine-Factor Profit Test

Below Groetzinger, auditors apply a more granular test drawn from Treasury Regulation 1.183-2(b). It lists nine factors meant to separate a real business from a hobby, no single one controls, and the burden of proof is on you.

Whether you operate in a businesslike manner, with separate accounts and detailed records.
Your expertise, including time spent studying game theory, odds, or coaching.
The time and effort you devote to the activity.
Any expectation that assets used in the activity will appreciate.
Your success in similar activities, including other businesses.
Your history of income and losses, and whether you adjust strategy in response.
The amount of occasional profits earned.
Your financial status, since offsetting a high salary with gambling losses looks like a shelter.
Elements of personal pleasure or recreation.

The Three-of-Five Profit Presumption

Section 183 adds a useful presumption. If your gambling shows a net profit in three out of any five consecutive tax years, the IRS presumes you are operating for profit, and the burden shifts to the government to prove otherwise.³ Failing the presumption does not automatically make your activity a hobby, but you will need the nine factors clearly on your side.

Records That Support the Claim

This is where most professional gambler claims fall apart. The IRS expects a contemporaneous diary or log capturing, for every session, the date and type of wager, the name and address of the establishment, the names of other people present, and the amounts won and lost.⁴ Along with the diary, keep W-2G forms, wagering tickets, canceled checks, bank withdrawal records, and any payment slips from the house. For online play, screenshots of account histories and transaction records do the same work.

The word “contemporaneous” is the one that matters. A log reconstructed from memory at tax time does not carry the weight of one kept in real time, and auditors can tell the difference. Business expense receipts need the same discipline: every hotel bill, gas receipt, meal charge, and tournament entry filed and linked to a specific session. Professional gamblers who survive audits tend to have systems that border on obsessive.

What Professional Status Changes on Your Return

Qualifying as a professional means you file Schedule C (Form 1040) as a sole proprietor, netting winnings against wagering losses and business expenses on a single form and paying tax on the profit.⁵ Casual gamblers do not get that treatment. They report all winnings as other income and can deduct losses only if they itemize on Schedule A, capped at winnings, which often leaves them paying tax on gross winnings with no offset.⁶

Deductible business expenses on Schedule C can include travel to venues, lodging on overnight trips, 50% of meals while traveling, tournament entry fees, data and strategy subscriptions, a qualifying home office, and professional fees for accountants or attorneys.⁷ Each item has to be documented; round numbers and estimates do not survive scrutiny.

The Schedule C profit is also subject to self-employment tax at a combined 15.3%, with the 12.4% Social Security portion applying only to net earnings up to $184,500 in 2026 and the 2.9% Medicare portion uncapped.⁸⁹ An additional 0.9% Medicare surtax applies above $200,000 for single filers or $250,000 for joint filers.¹⁰ Because no one withholds on winnings, professionals owe quarterly estimated payments covering both income tax and self-employment tax, and shortfalls accrue interest at 7% annually, compounded daily, in early 2026.¹¹

On the other side of the ledger, professionals filing Schedule C may qualify for the Section 199A qualified business income deduction, worth up to 20% of net profit from a domestic sole proprietorship.¹² It was set to expire after 2025 but was made permanent by the One Big Beautiful Bill Act. Professional gambling is not listed among the specified service trades or businesses whose deduction phases out at higher income levels, though the catch-all for businesses whose principal asset is the reputation or skill of the owner leaves some uncertainty for high-profile players.¹³

The 2026 90% Cap on Losses and Expenses

One recent change reshapes the math for anyone claiming professional status. Starting with the 2026 tax year, the deduction for gambling losses is capped at 90% of those losses, down from the prior 100%. The OBBBA enacted the change, and it applies to both professional and casual gamblers.¹⁴ The older ceiling also stays in place: deductible losses can never exceed winnings for the year.

For professionals, the effect is compounded. Business expenses such as travel, lodging, and tournament entry fees are grouped with wagering losses under Section 165(d), and the combined total faces the 90% cap. That grouping first came in through the Tax Cuts and Jobs Act for 2018 through 2025 and was made permanent by the OBBBA. A professional who breaks even on wagers but incurs $20,000 in business expenses can only deduct $18,000.

Practitioners call the result “phantom income.” Win $200,000, lose $200,000, carry no other expenses, and you deduct only $180,000 of losses; you owe tax on $20,000 that never stays in your pocket. The gap grows with the volume, and there is no carryforward to recover the disallowed 10% in a later year.

What Happens if the IRS Reclassifies You

When the IRS decides your gambling is not a trade or business, the consequences cascade. Your Schedule C is thrown out, your income is reclassified as hobby income, and your losses are only deductible if you itemize on Schedule A. Business expenses you claimed are disallowed entirely because hobby expenses are not deductible.

On top of the recalculated tax comes the 20% accuracy-related penalty, usually under the negligence or substantial understatement provisions.² Interest runs on the full balance from the original due date, compounding daily at the 7% rate in effect in early 2026.¹¹ For someone who claimed tens of thousands in business deductions over several years, the final bill can be staggering. Thin records plus gambling that looks more like recreation than work make filing Schedule C a wager likely to lose.

1
Justia Law. Commissioner v. Groetzinger, 480 U.S. 23 (1987)
2
Office of the Law Revision Counsel. 26 U.S. Code 6662 – Imposition of Accuracy-Related Penalty on Underpayments
3
Office of the Law Revision Counsel. 26 U.S. Code 183 – Activities Not Engaged in for Profit
4
Internal Revenue Service. Diary or Similar Record
5
Internal Revenue Service. 2025 Instructions for Schedule C (Form 1040)
6
Internal Revenue Service. Topic No. 419, Gambling Income and Losses
7
Internal Revenue Service. Publication 463 (2025), Travel, Gift, and Car Expenses
8
Internal Revenue Service. Self-Employment Tax (Social Security and Medicare Taxes)
9
Social Security Administration. Contribution and Benefit Base
10
Internal Revenue Service. Topic No. 560, Additional Medicare Tax
11
Internal Revenue Service. Interest Rates Remain the Same for the First Quarter of 2026
12
Internal Revenue Service. Qualified Business Income Deduction
13
eCFR. 26 CFR 1.199A-5 – Specified Service Trades or Businesses
14
Office of the Law Revision Counsel. 26 USC 165 – Losses