It can feel intrusive, but the question isn't optional curiosity — it's a legal box your bank has to tick before it can let the transaction through.
Yes. This isn't your bank being nosy by choice — it's legally required, under anti-money-laundering law, to ask about the source of larger or unusual deposits and withdrawals. Refusing to answer doesn't make the requirement go away; it usually just means the bank delays or refuses the transaction until it's satisfied it has done its own legal due diligence.
Neither US nor UK banks are asking out of personal curiosity or discretion — they're complying with their own legal obligations, and failing to ask can put the bank itself at legal risk.
| United States | United Kingdom | |
|---|---|---|
| Legal basis | Bank Secrecy Act and FinCEN rules | Money Laundering, Terrorist Financing and Transfer of Funds Regulations 2017 |
| Mandatory reporting trigger | Cash transactions over $10,000 require a Currency Transaction Report; anything smaller but still irregular can trigger a Suspicious Activity Report at the bank's discretion | No single fixed threshold — banks apply risk-based due diligence, escalating scrutiny for larger or unusual transactions per their own compliance policies |
| Can they ask below the reporting threshold? | Yes — the reporting duty is the mandatory floor, not the only trigger for questions; banks can still ask about smaller amounts that look unusual for the account | Yes — Financial Ombudsman decisions consistently support banks questioning source of funds even on transactions well under any fixed figure |
| Consequence of not answering | The bank can delay, refuse to complete the transaction, or in serious cases restrict the account while it investigates | Same — the bank can pause or decline the transaction rather than complete it without satisfying its own compliance duty |
Financial Ombudsman decisions on this exact issue are a useful reality check: cases where a customer felt genuinely offended by being asked about the source of a deposit or withdrawal have repeatedly been decided in the bank's favor, provided the bank acted reasonably and moved promptly once it got an answer. The frustration is understandable — but legally, this is closer to the bank following a mandatory checklist than making a judgment call about you personally.
Especially if it's noticeably different from your normal account activity, or involves cash specifically (cash is the highest-scrutiny category under AML rules everywhere). Have documentation ready if you can — it resolves this fastest.
Funds coming from someone else's account, especially larger amounts, commonly trigger a request for a gift letter, inheritance documentation, or sale paperwork. This is standard practice, not suspicion of you specifically.
Routine, in-pattern activity — your normal paycheck, a typical bill payment — shouldn't usually prompt this kind of scrutiny. If it does happen on something this ordinary, it's worth asking directly why.
A single, specific documentation request is normal. A pattern of repeated, vague, or escalating requests with no clear resolution path is worth escalating — ask explicitly what would satisfy the request and get that answer in writing.
The bank explains specifically what it needs (e.g. a gift letter, a sale document) and releases the transaction promptly once it's provided.
The bank asks vague, open-ended questions without specifying what documentation would actually resolve the hold, leaving the customer unsure what to provide.
The customer provides reasonable proof (payslip, gift letter, sale receipt) and the transaction proceeds within a clear, communicated timeframe.
The customer refuses to engage with the process at all, treating a compliance requirement as a personal insult — which typically just prolongs the delay rather than resolving anything.
Use Kibbo's Finance & Banking tools to put your documentation and escalation request in writing, with a clear timeline built in.
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