A one-tap "spin again" button placed directly under the reels produced 24% more £10 reload deposits in the 72 hours before payday than the same offer behind a two-screen checkout, according to a six-month A/B test across three UK-licensed slot brands. The effect was concentrated almost entirely between 00:00 and 03:00, when the uplift reached 31%. The same test found no statistically meaningful change in deposits at 10am on a Tuesday.

That is the uncomfortable shape of the finding. Friction that a product team would call "bad UX" is, in this specific window, the only thing standing between a player and a deposit they had not planned. Whether that counts as a design win or a harm depends entirely on which column you're reading, and the industry has spent the last three years pretending it can be both.

What the test actually measured

The setup matters, because "one-tap" is doing a lot of work in the headline. Three mid-size slot brands, roughly 40,000 monthly depositing players between them, split into a control and a variant for six months from September 2024 to February 2025. Both groups saw the identical £10 reload offer — same 35x wagering, same 7-day expiry, same eligible games. The only difference was the path from "offer seen" to "deposit confirmed."

The control group went through the existing flow: offer banner, offer detail page, deposit amount pre-filled, payment method selection, confirmation. Four taps and two full page loads on mobile. The variant collapsed this into a single button beneath the reels that opened a pre-authorised £10 deposit using the player's last-used payment method, with a confirmation sheet rather than a page.

The headline 24% figure is the lift in completed £10 deposits per active player across the full six months. The 31% figure is the same metric restricted to 00:00–03:00. Both are per-player rates, not raw totals, so the variant group wasn't simply bigger.

Two things the test did not show. It didn't show a change in the number of players depositing — the same people deposited, just more often. And it didn't show a lift in first-time depositors, who were excluded from the variant entirely because they had no stored payment method.

The payday effect is the whole story

Broken down by day of the month, the lift was flat for most of the cycle and then spiked hard in the last three days before the 28th, when a large share of the sample's salaries land. In that window the variant produced 24% more £10 deposits — the number in the title — but the deposits were smaller on average and more frequent. Median deposit in the variant group during the pre-payday window was £10; in the control it was £20.

That inversion is worth sitting with. Removing friction didn't make people deposit more per session. It made them deposit more often, in smaller amounts, which is the pattern most closely associated with the players gambling firms are supposed to be monitoring under the Gambling Commission's customer interaction rules. A £10 deposit is below most operators' own thresholds for a financial vulnerability check. Twenty of them in a week is not.

Why the friction was there in the first place

The four-tap flow wasn't an accident or a legacy system nobody had got round to. It was introduced in 2021, in most cases, as a direct response to the Commission's Remote Customer Interaction consultation and the subsequent guidance on "gambling management tools" and affordability. The extra screen was a deliberate pause — a place to surface deposit limits and a link to the player's account history.

The variant kept the limit link but moved it to the confirmation sheet, where it was seen after the decision rather than before it. In the test, 4.1% of variant players tapped through to set or review a limit, against 6.8% in the control. The difference is small in absolute terms and large in what it implies: the pause was doing work.

None of this is a secret inside the industry. Product teams have known for years that every additional step in a deposit flow costs conversion, typically 8–15% per screen on mobile. The 2021 changes were accepted because they were framed as a compliance cost. The question now is whether the same teams will treat the 24% as a conversion opportunity or as a warning.

The 1am problem

The time-of-day split is the part that should worry anyone signing off on a one-tap rollout. Between midnight and 3am, the variant group's average session length rose by 11 minutes and the number of deposits per player per session rose from 1.3 to 1.7. The control group was flat over the same period.

There's a well-worn argument that late-night players are simply a different, more engaged cohort and that the uplift reflects convenience rather than compulsion. The data here doesn't settle it. What it does show is that the pre-payday, small-stake, repeat-deposit pattern — the one the Commission's own guidance flags as a marker of harm — was materially more common in the variant group. That's not proof of harm. It is the exact behavioural signature operators are told to look for.

The counter-argument is that a £10 deposit at 1am is not, on its own, a problem, and that treating every late-night player as vulnerable is both patronising and commercially suicidal. That's fair. But the test didn't compare one-tap against a punitive wall. It compared one-tap against four taps. The 24% is the value of three taps.

What operators are likely to do with this

Some will ship the one-tap button and add a "cooling-off" prompt after the third deposit in 24 hours, which is the compromise most compliance teams will reach for. It's a reasonable compromise and it will probably claw back a chunk of the uplift, because a prompt after the third deposit is itself friction, arriving at the moment the variant is most effective.

Others will keep the four-tap flow and quietly accept the conversion loss, which is fine until a competitor doesn't.

The more interesting question is what the Commission does with evidence like this. The customer interaction rules are written around outcomes — are operators identifying and acting on harm markers — not around design. A one-tap deposit button is not, in itself, a breach of anything. But if the same operator can show a 31% uplift in 1am deposits and a documented fall in limit-setting, the gap between the letter of the rules and their intent gets harder to defend.

The number to watch isn't the 24%. It's whether the 4.1% limit-setting rate in the variant group holds up over twelve months, or drifts down as the button becomes the default. If it drifts, the industry will have found a way to make deposits easier and safer-looking at the same time — and the players who deposit £10 at 1am before payday will be the ones testing whether that's true. Anyone who finds themselves in that pattern can check where they stand with GamCare on 0808 8020 133, or set a deposit limit before the button gets a chance to be convenient.