Money already committed to premises, equipment, licences and staff, backed by the Canadian parent's financial statements, plus a realistic budget for the first year. Government fees on the USCIS schedule and professional fees are additional costs, not evidence of capacity.
Spend on the mill, then document the spending
Hypothetical example: a Haldimand County agri-food company is establishing a brand-new U.S. feed-blending site in leased premises and asks what it must have spent before petitioning for its manager. The new-office rules ask for secured physical premises and the financial ability to remunerate the transferee and begin doing business.
The convincing evidence is the signed lease, deposits paid, equipment purchase orders, state and federal registrations, initial inventory contracts, and a capitalization record showing funds moved from the parent into the U.S. account. Add the parent's audited or reviewed statements to demonstrate it can absorb a loss-making first year.
Immigration expenses themselves, including the I-129 filing fee, any fraud-prevention and other statutory fees on the current schedule, premium processing and legal fees, are budget lines, not evidence. Keep them out of the business plan's investment figures. A plan that shows spending on the operation, with hiring dates for the staff the manager will supervise, is what separates a supportable petition from a hopeful one.