Immigration Innovation Act of 2018 This bill amends the Immigration and Nationality Act to revise the formula for calculating the cap on H-1B nonimmigrant visas. It prohibits an employer from hiring an H-1B worker to replace a U.S. worker. The bill modifies the prevailing wage system by requiring that the first level of wages shall not be less than the lowest 50% of the wages surveyed. An employer may use an independent survey to determine the prevailing wage. For family-based visa petitions, the number of immigrant visas available to nationals of a single country may not exceed 15% of the total number of such visas made available in the fiscal year The bill establishes the Promoting American Ingenuity Account to enhance U.S. economic competitiveness by strengthening standards in science, technology, engineering, and mathematics (STEM), including computer science.