Substantial mobility in & out of poverty: 41 pct of those in poverty in 2007 were out of poverty in the following year; however, many of those who are poor spend multiple years in poverty or escape poverty only to fall back into it

Presence and Persistence of Poverty in U.S. Tax Data. Jeff Larrimore, Jacob Mortenson, David Splinter. Feb 2020. http://www.davidsplinter.com/LMS_PersistencePoverty_2020.pdf

Abstract: This paper presents new estimates of the level and persistence of poverty among U.S. households since the Great Recession. We build new annual household data files using U.S. income tax filings between 2007 and 2018. These data, which are constructed for the population of U.S. residents, allow us to track individuals over time and measure how tax policies affect poverty trends. Using an after-tax household income measure, we estimate that over 4 in 10 people spent at least one year in poverty between 2007 and 2018. Those that experienced at least one year of poverty spent an average of one-fourth of the 12-year period in poverty. There is substantial mobility in and out of poverty. For example, 41 percent of those in poverty in 2007 were out of poverty in the following year. However, many of those who are poor spend multiple years in poverty or escape poverty only to fall back into it. Of those who were in poverty in 2007, one-third are in poverty for at least half of the years through 2018. We also document substantial heterogeneity in these trends by age: younger individuals experience higher rates of poverty but less persistence; older individuals experience lower rates of poverty but more persistence.