This scientific analysis provides an estimate of the size of the informal economy in the Republic of North Macedonia, given the fact that the share of the informal economy in the gross domestic product reaches up to 35–40%—this share, which if not reduced, becomes a structural problem for the country’s economic system. This analysis brings a combination of direct and indirect methods, respectively; tax control is used as a direct method to measure the size of the informal economy, while in terms of indirect methods, the unemployment rate, currency demand, and Multiple Indicators Multiple Causes model are used. The high tax burden, low level of public services, low capacities of the Public Revenue Office, companies privileged by politics and state institutions, labor costs, and so on are considered the main reasons for tax evasion of companies that directly affect the informal economy in the Republic of North Macedonia.