Crypto and Gambling in Belgium: Is Polymarket Legal?
- Aeacus Lawyers
- Jan 14
- 7 min read
The use of crypto-assets in a gambling context has increased significantly in recent years. Foreign platforms allow users to place bets using cryptocurrencies on sports events, political outcomes, or other future developments. One of the most well-known examples is Polymarket, a so-called “prediction market” where users wager crypto on the likelihood of future events. Although such platforms often present themselves as innovative markets or information tools, the question arises how they should be legally classified under Belgian law. That classification leads to a clear, though for many surprising, conclusion: participation in Polymarket is illegal in Belgium and any resulting gains may be taxable.
What Is Polymarket and Why Is It Considered Gambling?
Polymarket allows users to take positions—effectively to gamble—using crypto-assets on the outcome of future, uncertain events. Users who predict correctly realise a gain; those who predict incorrectly incur a loss. The stakes are placed using crypto-assets, typically stablecoins. From a legal perspective, however, the means of payment is not decisive. What matters is that there is a stake, that the outcome is uncertain, and that a gain or loss may result.
The Belgian Gambling Act of 7 May 1999 adopts a particularly broad definition of gambling. As soon as these three elements are present, the activity in principle qualifies as a game of chance. The fact that Polymarket does not present itself as a “gambling website” but as a “prediction market” does not alter this legal assessment. Functionally, it constitutes gambling.
Crypto, Polymarket and the Belgian Gambling Act of 7 May 1999
The Belgian Gambling Act is based on a principle of prohibition. Games of chance are prohibited unless they are expressly authorised and licensed. The Belgian Gambling Commission is responsible for supervision and publishes, among other things, a list of illegal gambling websites that may not be offered in Belgium and are often effectively blocked.
The use of crypto-assets does not affect the applicability of this legislation. In this context, crypto-assets are considered assets of value that can be wagered. Gambling with crypto is therefore subject to the same legal framework as gambling with euros.
Why Polymarket Is Not Permitted in Belgium
Polymarket does not hold a Belgian gambling licence and is not authorised to offer games of chance to Belgian users. Moreover, since 30 January 2025, Polymarket has been explicitly classified by the Belgian Gambling Commission as an illegal gambling website and falls under the Belgian blocking and enforcement policy. As a result, access to the website from Belgium has been fully or partially restricted, in line with the established practice of blocking unlicensed gambling platforms. The Gambling Commission maintains and regularly updates a list of illegal gambling websites that may not be offered in Belgium.
The fact that a platform is established abroad, uses crypto-assets, or presents itself as “decentralised” does not provide any exemption. As soon as Belgian players are targeted, allowed to participate, or effectively participate, Belgian gambling law applies in full, regardless of the technical or legal structure promoted by the platform.
Participation in Unlicensed Gambling: What Does the Law Say?
The Gambling Act does not only target operators. Article 4, § 2 of the Gambling Act of 7 May 1999 expressly provides that it is prohibited for any person to participate in a game of chance, facilitate its operation, advertise it, or recruit players, where one knows that the game is unlicensed. In other words, the player themselves may also be in violation of the law.
In addition, Article 69 of the Gambling Act provides that all provisions of Book I of the Belgian Criminal Code apply to the offences defined in the Act. Participation therefore constitutes conduct that may give rise to criminal sanctions.
Are People in Belgium Actually Prosecuted for Participating in Polymarket?
As far as publicly available information indicates, there are currently no known court decisions in which Belgian individuals have been convicted specifically for participating in Polymarket. This does not, however, alter the illegal nature of the activity. The absence of known convictions does not imply that the activity is lawful; it merely reflects limited or selective enforcement.
A Common Misconception: Are Gambling Winnings Always Tax-Free in Belgium?
Many users assume that gambling winnings in Belgium are automatically tax-free. This assumption is legally incorrect. Belgian income tax law is based on the principle that all income is taxable unless an explicit exemption applies. Gambling winnings may in principle be taxed as miscellaneous income, for example where they result from speculation or from abnormal management of private assets.
The Distinction Between Authorised and Unauthorised Games of Chance
The fact that winnings from traditional games of chance such as Lotto, Euromillions or casino games are generally not taxed in practice is due to an administrative commentary issued by the Belgian tax authorities, namely commentary no. 90/8. This commentary provides that winnings from authorised tombolas and lotteries, including the National Lottery, as well as winnings from prediction contests, horse race betting and casino games, are not taxable. The commentary states in particular:
“the winnings from authorised tombolas and lotteries, including the National Lottery (lottery tickets such as Presto, Subito, 21, Scratch, as well as the Lotto and Joker games, Keno, Tele-kwinto), from prediction contests, from betting on horse races, from casino games, etc.”
The crucial nuance lies in the word “authorised”. This administrative tolerance applies exclusively to games of chance that are legally licensed and permitted in Belgium. In practice, the tax authorities almost systematically take the position that winnings derived from unlicensed or illegal games of chance do not fall within this tolerance and are therefore taxable. In other words, once a game of chance is not authorised, the resulting winnings are generally treated as taxable miscellaneous income.
Why Winnings from Polymarket May Be Taxable
Where a game of chance is not authorised, as is the case with Polymarket, reliance on administrative commentary no. 90/8 is not possible. In such circumstances, the tax authorities have a strong legal basis to tax the winnings as miscellaneous income. Such income is subject to a tax rate of 33 per cent, increased by municipal surcharges.
The argument that the proceeds constitute “gambling winnings” is therefore insufficient to avoid taxation. On the contrary, the illegal nature of the game may precisely lead to the inapplicability of the administrative exemption.
Can Losses from Illegal Gambling Be Deducted for Tax Purposes?
We take the position that, if the tax authorities consider winnings from unauthorised games of chance to be taxable, the associated losses should also be deductible. From a tax perspective, it is difficult to justify taxing gains without taking into account the economic reality of losses. In practice, however, this remains a contentious issue and may give rise to disputes with the tax authorities.
Banking Risk: Why Repatriating Winnings Is Often Problematic
Beyond the criminal law and tax risks, there is a significant practical issue. Banks are highly reluctant to accept funds originating from illegal activities. Even where a taxpayer is willing to declare the winnings correctly and pay the corresponding taxes, banks may refuse to accept such funds on the basis of their compliance and anti-money laundering obligations.
As a result, repatriating winnings from platforms such as Polymarket may prove extremely difficult or even impossible in practice.
The Paradox: Prohibited Crypto Gambling on Polymarket, Yet Taxable Winnings
This situation leads to a legally uncomfortable paradox. On the one hand, participation in unlicensed games of chance is prohibited. On the other hand, the resulting winnings may be taxed precisely because they fall outside the administrative tolerance applicable to authorised games of chance.
This creates an additional and very concrete problem. Taxes in Belgium must be paid in fiat currency and through the regular banking system. At the same time, banks—due to their anti-money laundering obligations and internal compliance rules—are often unwilling to accept funds originating from illegal gambling activities. Even where a taxpayer is prepared to declare the winnings correctly and pay the taxes due, the deposit or conversion of such winnings into a Belgian bank account may be refused.
The result is a paradoxical situation: a tax liability arises in respect of income that may not legally be generated and that, in practice, may be difficult or impossible to introduce into the regular financial system. The taxpayer may therefore face an obligation to pay taxes in euros on income that cannot readily be deposited into a bank account or used to satisfy that tax liability.
This tension between criminal law, tax law and banking compliance is often underestimated in practice, but it constitutes a real and significant risk for anyone engaging with prohibited crypto-gambling platforms.
Conclusion: Prohibited, Taxable and Practically Problematic
The legal position of crypto-gambling platforms such as Polymarket leaves little room for doubt in Belgium. Participation in such platforms is not permitted under Belgian gambling law. Since 30 January 2025, Polymarket has moreover been explicitly classified as an illegal gambling website by the Belgian Gambling Commission and falls under the applicable blocking and enforcement regime.
The tax reality is particularly counterintuitive for many users. The fact that a game of chance is prohibited does not prevent the tax authorities from taxing the resulting winnings. On the contrary, because the game is not authorised, the administration in practice almost systematically takes the position that the administrative exemption for authorised games does not apply. The consequence is taxation as miscellaneous income at a rate of 33 per cent, increased by municipal surcharges, while the deductibility of losses remains uncertain.
In addition, a very concrete practical problem arises. Taxes must be paid in euros and through the banking system, while banks often refuse to accept funds originating from illegal gambling activities, even where those funds are correctly declared and taxed. The taxpayer may thus be confronted with a tax liability on income that may not legally be generated and that may be difficult or impossible to repatriate in practice.
Anyone participating in prohibited crypto-gambling platforms therefore finds themselves simultaneously in breach of gambling law, exposed to tax liability, and dependent on banking goodwill that is often lacking. Ignorance does not alter this reality. For Belgian residents, participation in such platforms is therefore legally and practically highly risky.
If you have further questions regarding crypto taxation, please consult our Frequently Asked Questions (FAQ) or contact us to schedule an appointment.
Christophe Romero Senne Verholle
