Source of funds traces the actual purchase monies — the bank account, the sale of an asset, a gift, a loan — with supporting statements and paper trail. Source of wealth explains the bigger picture: salary and bonuses, a business sale, inheritance, investment returns. Regulated firms must satisfy themselves on both, proportionate to risk.
Enhanced checks apply to politically exposed persons, high-risk jurisdictions, complex structures and large cash elements. Expect to provide bank statements, contracts of sale, tax documents or a lawyer's letter — and expect questions where funds move through multiple accounts or countries.
Preparing this early is the single biggest accelerator of a clean completion. Gaps or unexplained movements are the usual cause of delay, and firms must decline or report where they cannot get comfortable.