Source of funds versus source of wealth: the difference, and why it matters.

Source of funds is where the specific money used in a transaction came from. Source of wealth is how the client built their overall net worth in the first place. They answer different questions, they are evidenced differently, and a firm can satisfy one while completely failing the other. Under MLR 2017, mixing the two up, or assuming one covers the other, is one of the recurring ways UK law firms fail an SRA file review.

What source of funds means.

Source of funds is the origin of the money actually being used in this transaction. If a client is buying a house for £450,000, source of funds asks: where did this £450,000 come from. A traceable answer might be the proceeds of a documented sale of a previous property, a specific inheritance evidenced by a grant of probate, or funds accumulated in a named savings account with a statement history that supports the figure.

What source of wealth means.

Source of wealth is broader: it is how the client accumulated their wealth overall, not just the funds in this specific deal. For a client with substantial assets, a firm may need to understand the general story of how that wealth was built, a long-running business, a career at a particular level of seniority, a prior liquidity event, before it can sensibly judge whether a given transaction fits the client's known profile.

A worked example showing the difference.

A client instructs a firm on a £450,000 residential purchase. Source of funds is satisfied by tracing the £450,000 deposit and any mortgage funds to a specific, evidenced origin. Source of wealth is a separate question: does it make sense that this client, generally, has access to funds at this level at all. A client who is a salaried employee on a modest income but is somehow purchasing several such properties in cash raises a source-of-wealth question that a clean source-of-funds trail for any single transaction will not, by itself, resolve. This is precisely why MLR 2017 treats the two as related but distinct enquiries rather than one combined check.

Why the two get confused.

Both checks sit within the same regulatory duty. Regulation 28(2)(c) of the MLR 2017 requires a firm to "assess, and where appropriate obtain information on, the purpose and intended nature of the business relationship or occasional transaction," and both source of funds and source of wealth flow from that same obligation, applied at different depths depending on risk. Because they are asked about in the same conversation with a client, and often evidenced with overlapping documents (a bank statement can speak to both), firms frequently treat a single enquiry as covering both questions when it has really only covered one, usually source of funds, leaving source of wealth unaddressed.

When each check is required.

Neither check is required to the same forensic depth on every matter. MLR 2017 sets a risk-based standard: the higher the money-laundering risk presented by the client and matter, the deeper the enquiry required (MLR 2017, Reg 28; LSAG guidance). Source of funds is expected wherever a transaction involves the movement of money and the risk assessment calls for it. Source of wealth becomes a specific, often mandatory, requirement in higher-risk situations: Regulation 33 of the MLR 2017 requires enhanced due diligence, including establishing source of wealth as well as source of funds, where a client is a politically exposed person or the matter involves a high-risk third country. Outside those higher-risk triggers, a firm's client and matter risk assessment (see our full CMRA explainer) should set out, and justify, how far the source-of-wealth enquiry needs to go for that specific client and matter.

How the SRA's own data shows firms getting this wrong.

The SRA's file reviews give a precise, and sobering, picture. Of the 5,026 files that required a source-of-funds check in 2024/25, 10% had none at all. Among the files where documents had actually been gathered, 18% were never scrutinised once collected, meaning the document sat on file untested. 8% contained source-of-funds information that did not match the client's ledger. Firms received source-of-funds feedback in 41% of the onsite inspections and desk-based reviews the SRA carried out that year, and 20% of the files rated non-compliant had a source-of-funds issue specifically (SRA AML Annual Report 2024/25). The SRA's own thematic review of source of funds and wealth compliance separately identifies the same clustering of failures: enquiry that leaves no trace, documents collected but not interrogated, and identity verification wrongly treated as if it answered the source-of-funds question too.

A firm can hold the bank statement, and still fail, if nobody checked whether the story it tells actually adds up.

What good evidence looks like for each.

For source of funds, the file should show: a specific, named origin for the money in this transaction; a document that evidences that origin (a completion statement, a probate grant, an account history); and a written note confirming someone checked the document against the client's account of events, not just filed it.

For source of wealth, where the risk rating calls for it, the file should show: a general account of how the client's wealth was accumulated, evidenced where practical (business accounts, employment history, a prior sale); and a reasoned note on whether that account is consistent with the scale of the current instruction. Neither needs to be forensic on a low-risk matter. Both need to exist, in proportion to risk, on a matter where the client and matter risk assessment says they should.

Why it matters.

Treating source of funds and source of wealth as one check, or assuming that clearing one clears both, is exactly the kind of gap an SRA file review is built to find. A file can have a perfectly evidenced source-of-funds trail for a single transaction and still miss a source-of-wealth problem that would have been obvious had anyone asked the broader question. Keeping the two conceptually and evidentially separate, and matching the depth of each to the client and matter risk assessment, is what turns a plausible-sounding answer into a defensible file.

Frequently asked questions.

Is source of wealth required on every matter.

No. It is required to a depth set by the firm's risk-based assessment of the client and matter, and is mandatory as part of enhanced due diligence under Regulation 33 where a politically exposed person or a high-risk third country is involved. On a low-risk matter, a firm may reasonably need very little beyond a general, evidenced account.

Does an electronic identity check satisfy source of funds or source of wealth.

No. Identity verification confirms who the client is. It does not establish where the money in a transaction came from, or how the client accumulated their wealth generally. The SRA treats this conflation as a recurring compliance failing.

What is the single most common source-of-funds failing UK firms make.

Based on the SRA's own 2024/25 figures, it is not a total absence of enquiry, it is enquiry that leaves no evidenced trail, or documents that are collected but never actually scrutinised once they are on file.

Can a firm rely on what the client tells them without independent evidence.

Generally, no, once the risk rating calls for a documented check. An unrecorded verbal explanation, however plausible, does not satisfy the regulations' expectation that customer due diligence is evidenced in a way a third party, including an SRA inspector, could follow.