Far enough to establish that the capital was lawfully earned and accumulated. In practice that usually means tax filings and employment or business records covering the years in which the contributions were made.
The container is not the source
Applicants often assume that a registered plan statement is itself the source-of-funds evidence, because the institution is regulated and the plan is visible. The requirement is about how the money was earned, so the plan statement establishes custody rather than origin. What answers the question is the earning history behind the contributions: assessments and returns for the relevant years, employment records or business financial statements, and the plan’s own contribution history connecting the two. Where the plan has been held for a long time, discuss with an adviser how much history is proportionate and what to do about years for which records no longer exist. Incomplete years are best identified and explained early rather than discovered during adjudication.
A first review should trace each dollar from its lawful origin through every account into the qualifying investment, while separately testing the job-creation evidence. Tax returns, sale documents, probate records, loan files, and bank statements answer different links in that chain. Sequence source proof before transferring capital. Problems arise when a legitimate asset sale is documented but the route from proceeds to the investment is incomplete. Hypothetical example: a wind-turbine technician uses proceeds from an inherited partnership interest; probate papers, valuation material, sale documents, and transfers must connect in order.