Statements showing the account balance, the withdrawal and the tax withheld, the deposit to the investor's bank account and the transfer to the project. Years of tax assessments explain how the account was funded.
Follow the money in both directions
Source of funds asks where the money came from originally; path of funds asks how it moved from there to the investment. For registered retirement savings the origin is employment income contributed over many years, so the file should include the couple's notices of assessment for a representative span of years showing income and contributions, and the account's annual statements. The withdrawal step generates a confirmation from the financial institution and a record of the tax withheld; keep both, because the amount deposited will be less than the amount withdrawn and the difference must be explained. Then the bank statement showing the deposit, and the wire confirmation showing the transfer to the project escrow or the new commercial enterprise, in the same amount. If the funds passed through a currency-exchange provider, include that provider's confirmation with the rate and fees. Every hop needs a document, and the sum of the hops must reconcile to the amount invested.
Hypothetical example: a quarry-equipment dealer is using proceeds from a long-held share portfolio and a parent’s gift. The first review should create two separate source-and-path charts, one for the dealer and one for the parent, each ending at the same investment wire. Brokerage statements, sale confirmations, tax records, gift documentation, and bank transfers settle the chain. Reconcile dates and amounts before filing; an unexplained transfer between otherwise documented accounts is still a gap the officer may question.