Source of Funds
Source of Funds is the evidence a licensed operator requires to confirm where the specific money a player is depositing and gambling with actually came from.
Definition
Source of Funds (SoF) is a customer due diligence check within an operator's anti-money-laundering (AML) programme, in which a player must document the legitimate origin of the money they are gambling with — for example salary, savings, an inheritance, or the proceeds of an asset sale. It is usually triggered when cumulative deposits, losses, or a single transaction cross a risk-based threshold, or when a player's activity looks inconsistent with what the operator knows about them, at which point it typically escalates into Enhanced Due Diligence (EDD). Acceptable evidence commonly includes recent payslips, bank or savings statements, tax returns, or documentation of a specific windfall, which the operator assesses to judge whether the funds are plausible and lawful. SoF is distinct from Source of Wealth (SoW), which concerns the origin of a person's overall net worth rather than the particular money in play, and from an affordability check, which asks whether the player can sustain the losses rather than whether the money is clean.
Worked example
Suppose a player deposits a cumulative £24,000 over two months and then requests a £6,000 withdrawal. Because the amount staked has crossed the operator's risk-based Source of Funds threshold, an analyst holds the payout and asks the player to evidence where the money came from. The player uploads three months of payslips showing net pay of about £2,000 a month — roughly £24,000 a year — plus a current-account statement. A £24,000 gambling spend in two months cannot be reconciled with a £24,000 annual salary and no visible savings, so the operator escalates to Enhanced Due Diligence, requests further documentation, and — if the gap stays unexplained — can restrict the account and file a Suspicious Activity Report (SAR). Had the player instead supplied a bank statement showing £50,000 in recent property-sale proceeds, the funds would likely be reconciled and the withdrawal released.
Why it matters
For players, SoF is the most common reason a large withdrawal is paused: licensed sites are legally required to check that gambling money is clean, so a request for payslips or bank statements is a compliance obligation, not an accusation or a stalling tactic. For operators and compliance staff, SoF is a front-line AML control and a frequent focus of regulatory enforcement — weak or undocumented checks have led to multimillion-pound fines and licence reviews — so knowing when to trigger it, what evidence to accept, and how it links to affordability and responsible-gambling duties is core to running a licensed business. Understanding SoF also reinforces that regulated gambling is never anonymous and that staked money is expected to be lost over time, which is why the regulator cares about the lawful origin of the funds rather than any potential for them to generate returns.
Related
Note: Jurisdiction- and operator-dependent. The trigger thresholds (cumulative deposits, losses, or single-transaction values), the timing, and which documents are accepted are set by each operator's risk-based approach and local rules — for example the EU Anti-Money-Laundering Directives, the UK's Money Laundering Regulations and Gambling Commission licence conditions — and change over time, so verify current requirements against the relevant regime. The £24,000/£5,000-style figures used above are illustrative, not standard trigger points. Note the important distinction between Source of Funds (origin of the specific money in play), Source of Wealth (origin of overall net worth), and affordability checks (ability to sustain losses); these are related but separate obligations and are frequently conflated in practice.