Polymarket operator Adventure One QSS Inc. has taken the Kansspelautoriteit (KSA) to court in The Hague over a €420,000 penalty, imposed after the prediction market stayed accessible to Dutch users one day past its ban deadline.
The appeal was first reported by Dutch financial daily Het Financieele Dagblad (FD). It follows the KSA’s rejection of Adventure One’s objection to the penalty.
One day over the deadline
The KSA issued a penalty order (last onder dwangsom) against Adventure One this year for offering illegal gambling in the Netherlands. The order gave the company until 17 February 2026 to stop serving Dutch players, with a penalty of €420,000 per week of non-compliance, capped at €840,000.
On 18 February, the regulator ran a check and found it could still log in and place bets on the platform. That triggered the first €420,000 instalment. The KSA issued a collection decree for the amount on 19 May 2026.
Polymarket withdrew from the Dutch market on 18 February, the same day as the KSA test. Adventure One says its blocks went live that day but had probably not been fully rolled out when the regulator checked, which it put down to technical factors.
The company told the KSA the measures were implemented “as quickly and carefully as possible within the short grace period.” It called the delay “not negligence, but a known feature of the technology.” The KSA did not accept that explanation, and the case now moves to court.
Gambling or financial product
Behind the deadline dispute sits a wider disagreement over what Polymarket sells. The company argues its event contracts are financial derivatives that belong under financial market regulation, outside Dutch gambling law. The KSA treats them as bets.
When the regulator announced the order in February, KSA director Ella Seijsener said:
“Prediction markets are on the rise, including in the Netherlands. These kinds of companies offer wagers that are simply not permitted on our market.”
Seijsener also pointed to the potential for prediction markets to influence elections. Polymarket had drawn Dutch media coverage over markets on election outcomes before the order was issued.
Polymarket has taken the same classification argument to Brussels, where it has lobbied for financial services status. US rival Kalshi is in talks with EU-level regulators, including the European Securities and Markets Authority (ESMA), according to SBC News.
Dutch parliament keeps the KSA line
A parliamentary attempt to create a separate regime has also failed for now. Dutch MP Iem Al Biyati submitted a motion to the House of Representatives calling for a dedicated framework to regulate prediction markets.
State Secretary Claudia van Bruggen rejected the motion, citing the KSA’s explicit view that these products constitute gambling. That leaves the regulator’s classification as the government’s position, and the court case as the main route left open to Polymarket in the Netherlands.
Blocks across Europe
The Netherlands is one of several European markets that have acted against Polymarket in 2026. Italy has put the platform back on its blocked list. Denmark included it among 98 gambling sites it blocked in August. Lithuania blocked Polymarket as unlicensed gambling in September, the first prediction market its regulator has blocked.
In France, Polymarket has filed a court challenge against its site block. The Dutch appeal is a separate challenge against a separate regulator.
Gibraltar has taken the opposite approach, adopting what it describes as the world’s first dedicated regulatory framework for prediction markets. Malta has signalled it may move in the same direction.
In the US, the Commodity Futures Trading Commission (CFTC) regulates prediction markets as financial instruments at federal level. A number of state regulators reject that designation and treat the products as gambling.
What happens next
No hearing date has been made public. If the KSA’s decision stands, Adventure One pays the €420,000, and the remaining €420,000 under the cap stays live should Dutch users reach the platform again.
For other offshore operators, the case will show how strictly a Dutch court reads a blocking deadline when a company says it acted on time and the technology lagged. For Polymarket, a loss in The Hague would land while it is still asking EU institutions to treat its product as finance.
Source: Kansspelautoriteit (KSA)
