No fixed universal dollar threshold exists. Substantiality is measured against the actual cost of the particular business, and nationality, the applicant's ability to direct the enterprise, and the enterprise's own operating requirements all need to be independently satisfied.
Understand what the investment amount is actually proving
Identify the specific business being purchased or formed and every cost the proposal includes. Flag expenses that fall outside a headline purchase price and separate firm estimates from payments actually made. A larger total investment does not repair an unresolved nationality question or a business that does not meet the operating-enterprise requirements.
The principal investor must separately show treaty nationality, qualifying national ownership of the enterprise, substantial capital irrevocably committed and at risk, a real nonmarginal operation, and development and direction through fifty percent ownership or operational control. Veto rights held by a minority, a management contract handing daily operations to an outside firm, or a class of shares carrying no vote can all leave a majority holder unable to direct anything.