How Does the IRS Define a Professional Gambler?

The IRS treats you as a professional gambler when your wagering activity qualifies as a trade or business rather than a hobby, and the controlling test comes from the Supreme Court’s 1987 decision in Commissioner v. Groetzinger: gambling is a trade or business when it is pursued full-time, in good faith, with regularity, and as a genuine source of livelihood.¹ There is no election, no checkbox, and no license. You either meet the standard or you don’t, and the burden of proving you do is on you. Claiming the status without meeting it exposes you to a 20% accuracy-related penalty on top of the taxes you already owe.²

The Groetzinger Standard

The Supreme Court’s Groetzinger case involved a full-time dog track bettor, and the Court held that a gambler wagering solely on their own account 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 emphasized that “constant and large-scale effort” combined with applied skill was what separated the taxpayer’s work from a hobby or an occasional bet for amusement.

That language remains the benchmark in every audit and Tax Court case on the question. If you gamble part-time while holding a full-time job, you face an uphill battle. If you can’t point to skill-based play and a real expectation of profit, sporadic trips to a casino won’t qualify no matter how much money changes hands.

The Nine-Factor Profit Test

Below the Groetzinger standard, the IRS applies a more granular test drawn from Treasury Regulation 1.183-2(b). The regulation lists nine factors designed to separate a real business from a hobby. No single factor controls; the IRS weighs them collectively.

Whether you carry on the activity in a businesslike manner, with separate accounts and detailed records. Sloppy or nonexistent bookkeeping is one of the fastest ways to lose professional status.
Whether you have real expertise, developed through study of game theory, odds analysis, coaching, or similar serious investment in your edge.
The time and effort you put in. Full-time commitment carries far more weight than weekend sessions.
Any expectation that assets used in the activity will appreciate. This matters less for most gamblers but can apply to tournament credentials that generate sponsorship income.
Your track record of success in similar activities, including past profitable businesses or prior success as a professional gambler.
Your history of income and losses in the activity. Years of consistent losses with no change in strategy cut against you.
The amount of any occasional profits. Even a single highly profitable year can help if it’s large enough relative to your losses.
Your financial status. If you have a high-paying day job and the gambling losses conveniently offset that income, the IRS is more likely to view the activity as a tax shelter.
Elements of personal pleasure or recreation. Everyone enjoys gambling to some degree; the question is whether recreation dominates and no credible business rationale exists.

The Three-Of-Five Profit Presumption

Section 183 gives you a procedural boost if you can meet it: when your gambling activity shows a net profit in three out of any five consecutive tax years, the IRS presumes you’re operating for profit.³ That shifts the burden to the IRS to prove otherwise. Failing the presumption doesn’t automatically make your activity a hobby, but you’ll then need the nine factors clearly on your side.

What Changes When You Qualify

Professional gamblers report all winnings and deduct wagering losses on Schedule C (Form 1040), the same form used by any sole proprietor.⁴ You net wins against losses on one form and pay tax on the profit. You can also deduct ordinary and necessary business expenses: travel to casinos and tournaments, lodging when you’re away from home overnight, 50% of business meals, tournament entry fees, subscriptions to data and strategy tools, a home office used exclusively for the business, and fees paid to accountants and attorneys.⁵

Casual gamblers get a much worse deal. They report all winnings on Schedule 1 as other income and can only deduct losses if they itemize on Schedule A. Those losses can never exceed winnings, and because the standard deduction often makes itemizing impractical, many casual gamblers end up paying tax on their gross winnings with no offset at all.⁶

The 2026 Loss Cap Changes the Math

Starting with the 2026 tax year, the deduction for gambling losses is capped at 90% of those losses, down from the prior 100%. This change was enacted through the One Big Beautiful Bill Act and applies to both professional and casual gamblers.⁷ The older ceiling stays in place too: deductible losses can never exceed your total gambling winnings for the year.

For professional gamblers, the impact is compounded. Business expenses (travel, lodging, tournament entry fees, and the rest) are grouped together with wagering losses under Section 165(d), and the combined total is subject to the same 90% cap. This grouping was originally introduced by the Tax Cuts and Jobs Act for 2018 through 2025, and the OBBBA made it permanent. A professional who breaks even on wagers but incurs $20,000 in business expenses can deduct only $18,000 of that total.

Practitioners call the result “phantom income.” Win $200,000, lose $200,000, and you can deduct only $180,000. You’ll owe tax on $20,000 of income that doesn’t actually exist in your pocket. The math worsens with scale, and there is no carryforward for the disallowed 10%.

Self-Employment Tax and Estimated Payments

Net profit on Schedule C is subject to self-employment tax, which covers Social Security and Medicare at a combined 15.3% rate: 12.4% for Social Security and 2.9% for Medicare.⁸ The Social Security portion applies only to net earnings up to $184,500 in 2026.⁹ Medicare has no cap, and an additional 0.9% surtax kicks in on self-employment income above $200,000 for single filers or $250,000 for joint filers.¹⁰

No employer withholds from gambling winnings, so professional gamblers make quarterly estimated tax payments covering both income tax and self-employment tax. The 2026 due dates are April 15, June 15, and September 15, 2026, and January 15, 2027; a due date falling on a weekend or holiday shifts to the next business day.¹¹ Underpaying triggers a separate penalty, and the IRS charges 7% annual interest, compounded daily, on any shortfall as of early 2026.¹² The safe harbor (paying at least 100% of last year’s tax, or 110% if your adjusted gross income exceeded $150,000) protects you even when income swings unpredictably.

Records That Hold Up

This is where most professional gambler claims fall apart. The IRS expects a contemporaneous diary or log that captures, for every gambling session, the date and type of wager, the name and address of the establishment, the names of other people present with you, and the amounts won and lost.¹³

The diary alone isn’t enough. Keep W-2G forms, wagering tickets, canceled checks, bank withdrawal records, and payment slips or statements from the establishment. For online play, screenshots of account histories and transaction records do the same work. The word that matters is contemporaneous. A log reconstructed at tax time from memory carries little weight next to one maintained 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 trip or session. Professional gamblers who survive audits tend to have systems that border on obsessive. That’s not a coincidence.

If the IRS Reclassifies Your Activity

If the IRS decides your gambling isn’t a trade or business, the consequences cascade. Your Schedule C is thrown out and your winnings are reclassified as hobby income. All winnings remain taxable, losses are only deductible if you itemize on Schedule A, and any business expenses you claimed are disallowed entirely because hobby expenses aren’t deductible.

On top of the recalculated tax, the IRS imposes a 20% accuracy-related penalty on the underpayment, typically under the negligence or substantial understatement provisions.² Interest accrues on the full balance from the original due date of the return, compounding daily at the 7% annual rate.¹² For someone who claimed tens of thousands in business deductions over multiple years, the total bill can be staggering. The best insurance is the same record-keeping described above, combined with a genuine profit motive backed by the nine-factor test.

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. 2025 Instructions for Schedule C (Form 1040)
5
Internal Revenue Service. Publication 463 (2025), Travel, Gift, and Car Expenses
6
Internal Revenue Service. Topic No. 419, Gambling Income and Losses
7
Office of the Law Revision Counsel. 26 USC 165 – Losses
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. When Are Quarterly Estimated Tax Payments Due?
12
Internal Revenue Service. Interest Rates Remain the Same for the First Quarter of 2026
13
Internal Revenue Service. Diary or Similar Record