Gamblers who spend more than £1,000 online in a 24-hour window will have to undergo a financial risk assessment, the industry regulator has announced.

The Gambling Commission said this would also apply to anyone spending over £3,000 in a rolling 90-day period. Under-25s will have lower thresholds.

The assessments will be based on data held by credit reference agencies, but the commission has insisted they are not “affordability checks”.

The Betting and Gaming Council, which represents gambling firms, said it was “disappointed and frustrated” with the changes, which they said could push customers towards the black market.

The commission has not set a timeline for the changes saying they will be introduced in a “very careful, staged way”.

It said there was evidence some high-spending customers were experiencing financial difficulties but not being identified or supported by bookies.

The checks will start with over-25s who gamble more than £5,000 in a rolling 24-hour period. Initially, they will only apply to the largest gambling companies .

The watchdog said the first stage will affect less than 0.5% of customers and will be rolled out this summer, following engagement with the industry and other stakeholders.

The threshold will eventually be lowered to £1,000 in 24 hours, or £750 for under-25s.

In 2023, a white paper on gambling recommended enhanced checks on customers experiencing very high losses.

On Tuesday, the commission said high-spending gamblers were between two and four times more likely to have a debt management plan, and between two and five times more likely to have a default in the previous 12 months than consumers in the wider population.

The acting chief executive of the Gambling Commission, Sarah Gardner, said the vast majority of customers would never require an assessment.

Those who do would have a frictionless, document-free assessment provided by credit reference agencies, with no impact on their credit score.

She said the commission believed this approach “will enable support for high-spending customers in financial difficulties, while reducing friction for customers who are not”.

The commission has insisted that the assessments are not the same as affordability checks, which Gardner said were “deeply unpopular” with gamblers.

She added that stakeholders had expressed concerns that more regulation could push problem gamblers onto the black market.

The Gambling Survey for Great Britain, external found that in 2024, 9.3% of adults who gambled online – excluding those who took part in lotteries – had a score of eight or more on the Problem Gambling Severity Index. The index goes up to 27.

A score of eight or more means a person “may have lost control of their behaviour” and have experienced adverse consequences from gambling.

The commission said it was still seeing failures in enforcement, and recently found a case of a customer who deposited £25,000 in 25 days before being interacted with.

Gambling Minister Baroness Twycross said the assessments must work for “consumers, gambling operators and the wider ecosystem”.

But the Betting and Gaming Council said it was “deeply disappointed and frustrated” that the Gambling Commission was backing risk assessments “despite the significant concerns raised over the last 18 months by the BGC, operators, racing, parliamentarians and customers”.

Its chief executive, Grainne Hurst, said: “The central issues around reliability, consumer impact and the practical operation of these checks remain unresolved.”

She said the Gambling Commission has not provided enough “accurate, reliable or consistent” data to support the checks.

“We support evidence-led, proportionate regulation that protects vulnerable people while allowing the 22.5 million adults in Britain who bet each month to do so safely.

“But until the Commission can demonstrate these checks are accurate, consistent and genuinely frictionless, our fundamental concerns remain, including the risk of driving customers towards the growing illegal gambling market.”

The British Horseracing Authority also criticised the announcement, saying the changes would “subject racing bettors to unwarranted levels of intrusion”.