Two questions, not one
Institutions ask two different things and often use the terms loosely. Knowing which is being asked saves you a great deal of wasted effort.
Source of funds is about the specific money in front of them. Where did these particular coins, or this particular payment, come from? The answer is a transaction trail.
Source of wealth is broader. How did you come to have money at all? The answer is a life story with documents: your occupation, your income over time, an inheritance, a business sale.
A large transfer usually triggers the first. Becoming a high-value client, or moving a sum that looks out of proportion to your visible income, triggers the second. If you are unsure which you have been asked for, ask them to clarify in writing.
The institution is not trying to understand you. It is trying to satisfy an obligation to document that your money has a lawful and plausible origin, in a form that survives its own audit. That is why explanations fail and documents work. Your goal is to make their file complete, not to be believed.
What actually counts as evidence
Works
- Bank statements showing the money leaving your account to buy
- Exchange transaction history and account statements, downloaded as PDF
- Purchase confirmations and trade receipts
- Payslips and employment contracts
- Tax returns, especially ones declaring the holdings
- A sale contract for a property, business or vehicle
- Inheritance or probate documents
- A signed gift letter with the giver's details
- Invoices, if you were paid in Bitcoin for work
- Mining records: pool payouts, equipment invoices, electricity bills
- On-chain transaction IDs linking a documented purchase to your wallet
Does not work
- An explanation with nothing attached
- Screenshots with no identifying detail or dates
- A wallet balance, which shows what you have, not where it came from
- Documents in a language they cannot read, untranslated
- A narrative that does not match the documents you attached
- Anything edited, backdated or reconstructed
- "I bought it a long time ago" with no supporting trace
Build the file now
Write the timeline first
A single document, one line per acquisition: date, amount in BTC, how acquired, from whom or which platform, what you paid, and which document proves it. Start at the beginning and work forward.
Writing this is how you discover what is missing, and missing records are far easier to obtain today than in five years when the platform has closed.
Export everything from every exchange, including dead ones
Full transaction history, account statements, deposit and withdrawal records, in PDF where possible. Do this for every platform you have ever used, including ones you no longer touch.
Exchanges close, get acquired, delist countries and delete old records. A platform you used years ago may already be gone, and with it the only proof of a purchase. This step alone justifies the afternoon.
Collect the bank side
For each purchase, the statement showing money leaving your bank. This is the link most institutions actually want, because it ties the crypto to the regulated financial system they understand.
Many banks only keep statements online for a limited period. Download and store them yourself.
Record the on-chain link
For significant acquisitions, note the transaction ID of the withdrawal from the exchange to your wallet, and the receiving address. This connects the documented purchase to the coins you actually hold.
Store this in your private file. Do not publish it, and be deliberate about who you hand it to, since an address discloses a permanent transaction history.
Document the awkward cases while you still can
Peer-to-peer purchases, coins received as payment, gifts, mining. These are the ones that sink applications, and the evidence usually still exists today.
- P2P purchase: the platform's trade record, chat log, the bank transfer, and the counterparty's details if you have them
- Paid in Bitcoin for work: the invoice, the contract, and the tax return declaring the income
- Gift: a signed letter from the giver stating the amount, date and that it was a gift, with their identity details
- Mining: pool payout records, hardware invoices, electricity bills, and the tax treatment you applied
- Cash purchase or ATM: whatever receipt exists, plus evidence of where the cash came from. This is the hardest category, so document it now rather than later
Add the tax layer
Tax returns declaring your holdings or your gains are among the strongest documents you can produce, because they are statements to a government that carry consequences if false.
If you have declared properly, the file is easy. If you have not, that is a separate problem that a source of funds request will eventually surface, and it is much better addressed before someone else raises it.
Store it properly
One folder, organised by year, with the timeline document at the top. Keep it encrypted, keep an offline copy, and review it once a year when you review your other estate documents.
This file describes your holdings and your history. Treat it as sensitive.
Handling an actual request
Answer exactly what was asked. If they want documentation for one deposit, send that. Do not volunteer your whole history. Over-disclosure creates new questions and a larger permanent record.
Lead with a short cover note. Two or three sentences stating what the funds are, when acquired, and what you have attached. Then the documents, clearly labelled. Compliance staff process many of these, and a legible submission moves faster.
Be honest about gaps. "I bought this several years ago through a platform that no longer exists. I have the bank statement showing the payment but not the platform record" is a workable answer. A confident story unsupported by the attachments is not.
Translate where needed, and say what each document is if it is not obvious.
Do not create, edit or backdate a document to fill a gap. It moves you from a compliance question into fraud, in essentially every jurisdiction. Compliance teams cross-check documents against each other specifically to detect this, and an incomplete honest file is vastly better than a complete false one.
When to involve a lawyer
- The sum is material relative to your net worth
- You are asked for source of wealth rather than source of funds
- The questions read like an investigation rather than a form
- There is a tax exposure you have not resolved
- Law enforcement is mentioned in any way
- The funds involve a jurisdiction with sanctions or high-risk designations
In several of those situations, what you write becomes evidence. Get advice before you write it, not after.
The short version
- Build the file before anyone asks. It is an afternoon.
- Export from every exchange, including ones you no longer use.
- Bank statements are the link institutions care about most.
- Documents beat explanations, always.
- Honest gaps beat invented completeness, always.
- Answer what was asked and nothing more.
- Review it once a year.
Everything here is written to stay true. It explains how the machinery works rather than what today's numbers are, because thresholds, rates and deadlines change every year and a stale legal page is worse than no page at all. Where a current figure matters to your decision, this page tells you how to find it rather than guessing on your behalf.
General information, not legal advice. This site does not provide legal advice, and no professional or advisory relationship is created. Anti-money laundering requirements, evidentiary expectations, record retention periods and tax obligations vary substantially between jurisdictions and change over time. What a particular institution will accept is its own commercial and regulatory judgment. Consult a qualified lawyer or tax adviser licensed where you live, particularly where a material sum or an unresolved tax position is involved.