The report found significant differences between projected GDP, which measures the level of production in the U.S., and gross national product, which measures the income earned by all Americans. If the economic impact from GDP is higher than GNP, the difference between the two is income generated in the United States but going to foreigners. According to the CBO, on average 34 percent of income from the economic activity driven by the tax cuts is flowing out of the country, and in 2028, when the full effects of the tax cuts are in place, that number will increase to 80 percent.