The term “substantial” is not strictly defined. However, the general rule is that the amount of investment should be sufficient to enable the business to operate successfully, and in most instances, will be significant in relation to the overall cost of acquisition or creation of the business. The capital must be sufficient to enable the business to function and generate revenue. There is not an exact dollar amount that is mandated, but in the smaller business range, the investment can expect to be in the tens or hundreds of thousands of dollars. In addition, the capital must be at risk, and the business must not be marginal (or providing only a means of non-employment for the investor and their family, but ideally, employing U.S. workers as well).