What is a sticky bonus?
A sticky bonus (also called a non-cashable or locked bonus) is a bonus that can be used for wagering but cannot itself be withdrawn. Only the winnings generated from it can be cashed out after wagering requirements are met. The bonus funds themselves disappear from your balance when you withdraw.
How a sticky bonus works
Receive £100 sticky bonus. Wager it through (say 30x = £3,000 in total bets). Suppose you end with £200 in your account. Withdraw £100 — the £100 bonus is removed (it was sticky) and you get £100 in real withdrawable winnings. Versus a non-sticky (cashable) bonus where the full £200 would be yours after wagering.
Sticky vs non-sticky value
Non-sticky bonuses are better for the player because the bonus amount itself can be withdrawn after wagering. Sticky bonuses are more common now because they reduce the casino’s risk — players can’t simply complete wagering at low variance, then withdraw the full balance including the bonus. When comparing bonuses, check whether the bonus is sticky or non-sticky, as this significantly affects actual value.