Many players will not know much about the term "source of funds". This is a proof of the origin of the money deposited in the online casino. This means that the respective Player is supposed to prove that the original Deposit amount did not come from illegal activities, for example.
Normally, an Online Casino requires proof of the origin of the money when larger amounts of money are deposited or withdrawn. In this case, the user must prove where the deposited money comes from. The easiest way to do this is, for example, by providing a current pay slip for the past few months. Another possibility is that the money deposited was given as a gift or inherited. In this case, too, players are required to provide written proof of this. Usually, however, corresponding proof of the origin of funds is actually only requested for higher transaction amounts.
As a rule, online casinos are obliged by the licensing authority (e.g. MGA) to demand this proof. Otherwise, they Risk a penalty payment or, in the worst case, a license revocation. The aim is to ensure that each player only plays within his own financial means. In addition, the aim is to prevent gambling with funds derived from illegal activities such as drug or arms trafficking. Money laundering is also to be made more difficult by this control mechanism.
If a player has deposited significantly more money than his monthly income would allow, this does not necessarily mean that he will not be paid his possible win. In this case, it is possible, for example, to send the online Casino a statement of his savings account, if there is sufficient capital there. In case of questions or problems, the player in question can of course ask the customer service of the respective online casino for help at any time.