There is no fixed minimum or bright-line percentage. The investment is weighed against the total cost under an inverted proportionality test, so a lower-cost business generally requires a higher invested percentage. Seller financing secured by the business is excluded from counted capital and can change the result.
Substantiality is a proportion, not a threshold
Hypothetical example: the shop's agreed price is set out in the purchase agreement, supported by an independent valuation. If the couple fund the entire price from savings and the home-equity line, the invested amount equals the cost of the enterprise and substantiality is straightforward. If instead they pay sixty percent in cash and the seller carries forty percent secured against the shop's assets, only the sixty percent counts, and the file must analyze that qualifying amount against the shop's actual cost.
There is no bright-line percentage, so whether sixty percent is substantial depends on the cost of the enterprise, the magnitude of the qualifying funds and the evidence of commitment; the seller note also adds a creditor with a claim on the enterprise. Government charges are the consular visa application fee and any reciprocity fee, published by the State Department, not the USCIS schedule, because Canadians apply at the consulate.