The Complete Arbitrage Betting US Tax Guide: US Tax Implications For Prediction Market And Arbitrage Profits

Arbitrage Betting US Tax Implications: Who This Guide Is For

This guide is written for two distinct audiences: casual participants who occasionally place opposing bets across platforms to capture a pricing gap, and organized arbitrage traders who systematically scan multiple bookmakers or prediction market platforms, use dedicated tools, and treat the activity as a repeatable profit source.

The US tax analysis differs significantly between these groups, and understanding which category applies to your situation is the starting point for any honest assessment of your reporting obligations.

Arbitrage betting — often called “arb betting” or surebetting — involves identifying pricing discrepancies across bookmakers or prediction market platforms for the same underlying event. By placing opposing positions simultaneously, such as buying the “Yes” outcome on one platform and the “No” on another, a trader can theoretically lock in a guaranteed profit when a genuine odds mismatch exists and the event resolves cleanly.

The strategy has gained renewed attention in the US with the growth of regulated sports betting and the emergence of prediction markets such as Polymarket and Kalshi. For US participants, however, the strategy is only as clean as the tax analysis underneath it.

The IRS requires reporting of gambling-related profits, and the correct characterization (casual gambling income, business income, or potentially capital gains) depends on how the activity is conducted rather than how the participant labels it.

Prediction Markets vs Traditional Arbitrage: Important Distinctions

Traditional arbitrage typically involves sportsbooks with near-instant resolution. Prediction markets often feature longer-duration events (e.g., elections, economic indicators) and may raise additional questions around capital asset treatment or §1256 contracts on regulated platforms. Understanding these differences helps you better assess your own tax position.

Platform-Specific Notes

• Kalshi (CFTC-regulated): Cash-settled event contracts may qualify for §1256 treatment (60/40 long-term/short-term capital gains) in some cases, though this remains unconfirmed by specific IRS guidance.
• Polymarket and similar crypto platforms: Crypto-based positions trigger property disposition rules on every transaction (acquisition, settlement, conversion), creating multiple taxable events separate from the underlying arbitrage profit.

Example Impact of 2026 90% Loss Limitation (Recreational): $10,000 winnings and $9,000 losses → You can deduct only $9,000 (but capped at 90% of winnings = $9,000), resulting in $1,000 phantom taxable income even on near break-even activity.

Bottom Line on Arbitrage Betting Tax Treatment in the US

For most casual bettors and occasional arbitrage participants, winnings from prediction markets and arbitrage betting are fully taxable as gambling income (reported on Schedule 1 as Other Income). Losses are generally deductible only to the extent of winnings if you itemize on Schedule A, and starting in 2026, subject to a 90% limitation under the One Big Beautiful Bill Act (OBBBA) changes to §165(d). This can result in tax owed even on low-risk or break-even activity.

However, if you engage in arbitrage betting or prediction market trading in a systematic, professional manner — such as treating it as a repeatable profit-making venture with dedicated time, tools, and significant volume — the IRS may classify the activity as a trade or business.

In that case, you would report on Schedule C, where net profits are subject to income tax plus self-employment tax (approximately 15.3%), but broader business expenses may be deductible (still subject to the 90% wagering loss limitation in 2026). The distinction ultimately turns on the specific facts of your situation, including profit motive and business-like operation.

Why Professional vs. Recreational Matters When All Gambling Income Is Taxable

You may ask: if all gambling winnings are taxable in the U.S., why does it matter whether I’m classified as a recreational or professional gambler? The distinction is critical because it affects how you report income, what you can deduct, and what taxes you pay.

Recreational Gambler

• Reports gambling winnings on Form 1040, Schedule 1, Line 8 as “Other Income”
• Can deduct gambling losses only up to the amount of winnings (as a miscellaneous deduction on Schedule A, if you claim itemized deductions)
• Cannot deduct business expenses (software, data feeds, home office, etc.)
• Not subject to self-employment tax
• Losses beyond winnings cannot offset other income

Professional Gambler

• Reports gambling income and expenses on Schedule C (Form 1040) as self-employed business income
• Can deduct all ordinary and necessary business expenses, including software subscriptions and trading tools, data feeds and analytics services, internet and home office expenses (if applicable), professional fees, and bank and transaction fees
• Can deduct net losses against other income (subject to excess business loss limitations)
• Subject to self-employment tax (15.3% on net earnings)
• Must pay both income tax and self-employment tax on net profits

The key takeaway: recreational gamblers pay tax on winnings minus losses up to winnings, while professional gamblers pay tax on net income (winnings minus all losses and expenses) and can use losses to offset other income.

How the IRS Applies the Professional-Gambler Test: Key Factors

The IRS distinguishes recreational gambling from professional gambling using a consistent set of factors derived from decades of case law, including the Supreme Court’s decision in Commissioner v. Groetzinger (1987). Key factors include:

• Primary source of income: Are you gambling full-time and relying on it as your main income?
• Frequency and volume: Do you execute hundreds or thousands of trades/bets annually?
• Organization and system: Do you use specialized tools, software, or systematic strategies?
• Time commitment: How many hours per week are devoted to the activity?
• Specialized knowledge: Do you have training or expertise in odds analysis, market inefficiencies, or risk management?
• Profit motive: Is your primary intention profit, not entertainment?
• Business-like operations: Do you maintain detailed records, use separate accounts, track P&L?

The IRS looks at the totality of circumstances. A taxpayer who scans multiple platforms daily using automated tools, maintains detailed profit-and-loss records, and withdraws consistent profits faces a strong likelihood of being classified as a professional gambler.

For arbitrage bettors, the risk-elimination design of the strategy is both its greatest operational strength and its greatest tax liability simultaneously. The systematic, risk-free nature of arbitrage is exactly what pushes the IRS toward professional-gambler classification.

Capital Gains vs. Business Income for Prediction Market Participants

A distinction that sophisticated U.S. participants should understand is that prediction market profits are not automatically characterized as business income. Depending on the frequency, duration, and intent behind the positions held, some participants may argue that their prediction market activity generates capital gains rather than business income. The distinction is significant: long-term capital gains attract lower tax rates (0%, 15%, or 20%), and the loss treatment differs materially from business income.

The IRS’s likely response to a capital gains argument from an active prediction market trader is skeptical. The short duration of most prediction market contracts, the high frequency of typical trading activity, and the deliberate profit-seeking nature of arbitrage across platforms all point toward a trading-inventory characterization that attracts business income treatment rather than capital property treatment.

A participant holding a small number of longer-duration prediction market positions — such as annual economic or political contracts — has a more defensible capital gains argument than one executing daily cross-platform arbitrage.

Where the activity is neither clearly business income nor clearly capital gains, the analysis turns on whether the activity meets the continuity and regularity test for a trade or business. An experienced U.S. tax professional should be consulted before adopting a reporting position in this grey zone.

IRS Tax Rules for Arbitrage Betting and Prediction Markets in the US

Casual gambling winnings are reported as Other Income, with losses limited. Prediction markets add complexity due to possible characterizations as gambling income, capital assets, or §1256 contracts (60/40 treatment for certain regulated event contracts). Cryptocurrency or foreign elements require careful fair market value tracking at each transaction step, with each crypto disposition as a separate taxable event.

“The key point is simple: arbitrage betting is only risk-free until the tax question shows up. In the U.S., the label matters far less than the facts — how often you trade, how organized you are, and whether you are conducting the activity like a business. The real issue is whether the IRS determines your overall betting or trading activity constitutes a trade or business” — David Rotfleisch, a certified Specialist in taxation and founding tax lawyer at Rotfleisch & Samulovitch P.C.

Key Takeaways on Arbitrage Betting Taxation in the U.S.

The tax treatment of arbitrage betting and prediction market profits in the U.S. is not determined by the nature of the activity in isolation — it is determined by how the IRS characterizes the specific taxpayer’s conduct. Casual, occasional participants who dabble in arbitrage without system or significant volume may still be classified as professional gamblers if the activity is system-driven and risk-free.

Organized, high-frequency participants who rely on arbitrage or prediction market profits as a meaningful income stream — and whose activity is specifically designed to eliminate risk through system — face the strongest likelihood of being classified as professional gamblers.

Participants using offshore platforms should assess their FBAR and Form 8938 filing obligations regardless of how the underlying profits are characterized. Those using crypto-denominated platforms should document all cryptocurrency transactions and understand the property-disposition mechanics.

Participants whose accounts have been restricted or banned by platforms face additional evidentiary exposure. And participants whose activity sits between capital gains and business income should obtain professional advice before filing, as the reporting position adopted in the first year can be difficult to reverse if the IRS disagrees.

The prudent approach is to treat the tax question with the same rigour applied to the strategy itself. That means maintaining complete records from the outset, understanding the cryptocurrency and foreign reporting obligations where relevant, addressing the self-employment tax question where the activity may constitute a trade or business, and retaining an experienced U.S. tax professional before an IRS audit or reassessment arrives rather than after.

Pro Tax Tips for Arbitrage Bettors and Prediction Market Participants in the U.S.

The most important — and most overlooked — step for active arbitrage participants is to conduct an honest annual self-assessment against the professional-gambler factors before filing. This is not a formality. If your activity has grown in volume, organization, or profit reliance since the prior year, the characterization that applied last year may not apply this year. Catching that shift proactively allows you to file correctly.

For participants using cryptocurrency-denominated prediction markets, purpose-built crypto tax software — reviewed and reconciled by a qualified professional — is worth the investment. A dedicated cryptocurrency wallet and bank account used exclusively for arbitrage activity creates the clean audit trail that any credible filing position requires.

Participants holding balances on foreign platforms should calendar their FBAR and Form 8938 filing obligations alongside their annual return. The $10,000 FBAR threshold applies to the maximum aggregate value during the year. And participants who have had accounts restricted or closed by platforms for arbitrage activity should document those events carefully — the restriction itself may become relevant evidence in any future IRS characterization dispute.

Arbitrage Betting US Tax FAQ

Are arbitrage betting or prediction market winnings taxable in the US?

Yes. For casual participants, profits are generally treated as taxable gambling income (Other Income on Form 1040). Losses are deductible only to the extent of winnings if you itemize (subject to the 90% limitation starting in 2026). For organized, business-like activity, profits are reported on Schedule C as business income, subject to self-employment tax, with broader (but still limited) deduction opportunities.

Do I need to report arbitrage or prediction market profits on my US tax return?

Yes, all winnings/profits must be reported regardless of whether a Form 1099 or W-2G is received. Casual players report gross winnings; business characterization allows netting and expense deductions on Schedule C. Professional guidance is recommended for borderline or high-volume activity, especially with prediction markets.

What records should I keep for arbitrage betting in the US?

Comprehensive records are essential and should include platform transaction histories, account statements, bet confirmations or screenshots, bank and cryptocurrency transfer records, fees paid, currency conversions at fair market value, and a summarized profit-and-loss ledger by tax year. Records should be retained for the IRS statute of limitations period (typically at least three to six years).

Can losses from arbitrage betting be deducted in the US?

For casual gamblers, losses are deductible only up to the amount of winnings (itemized on Schedule A, with the 90% cap in 2026). For business (professional) gamblers on Schedule C, losses and expenses can offset income more flexibly as part of the net business profit calculation (still subject to limitations).

Does cryptocurrency complicate the tax treatment of prediction market profits?

Yes. Crypto transactions are treated as property dispositions, creating taxable events based on fair market value at each step (acquisition, use for positions, settlements, and conversions). Detailed contemporaneous tracking is required, and digital asset brokers may issue Form 1099-DA.

Do I need to consider other reporting obligations?

Platforms may issue Form 1099 series or W-2G for reportable activity. High foreign or crypto holdings may trigger FBAR, Form 8938, or other information returns. Prediction market characterization (gambling vs. capital vs. §1256) remains an evolving area without comprehensive guidance. State taxes may also apply differently.

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.