The World Bank assigns the world’s economies into four income groups — high, upper-middle, lower-middle, and low. We base this assignment on GNI per capita calculated using the Atlas method. The units for this measure and for the thresholds is current US Dollars. At the Bank, these classifications are used to aggregate data for groups of similar countries. The income-category of a country is not one of the factors used that influence lending decisions. Each year on July 1st, we update the classifications. They change for two reasons: In each country, factors such as income growth, inflation, exchange rates, and population change, influence GNI per capita. To keep the dollar thresholds which separate the classifications fixed in real terms, we adjust them for inflation. The data for the first adjustment come from estimates of 2016 GNI per capita which are now available. This year, the thresholds have moved down slightly because of low price inflation... — blog.wb.org/blogs