Bank records showing money leaving the buyers' accounts and arriving with the seller or an escrow agent, the purchase agreement with its conditions, and evidence of what was bought. Statements of intention prove nothing. Funds must be irrevocably committed, not merely available.
The trail has to end somewhere irrevocable
The requirement people underestimate is irrevocability. Capital sitting in the buyers' account, earmarked for a purchase that has not closed, is not an investment; it is savings with a plan attached. What the file needs is a continuous documentary trail: the source of the money, its movement between accounts, the transfer out, and its arrival at a destination from which it cannot simply be recalled.
In a purchase, escrow subject to defined release conditions usually does the work. Alongside that sit the commercial documents: the purchase agreement, the allocation of the price between equipment, goodwill and inventory, the assignment of the customer contracts, the vehicle transfers and the lease. Where a portion of the price is financed, the security matters, because borrowing secured on the assets of the enterprise being acquired is not treated as the investor's own capital at risk.
A loan secured on the buyers' Erin property, by contrast, puts their own assets on the line and is ordinarily counted.