Though it avoids the word "underclass", the study, published by the Centre for Economic Performance at the London School of Economics, finds there is a large group of people who move in and out of jobs but remain in poverty.
Jobs, Wages and Poverty identifies a social group, in author Paul Gregg's words, "constantly cycling between low-paid employment and worklessness".
The problem is not that they do not want to work, but that the kind of jobs they find, often seasonal, part-time, or casual, are short-term, and those employed in this way will soon become unemployed again.
A "snapshot" of numbers in employment - often used by government ministers to bolster claims of economic recovery - often overstates the extent to which jobs last. Even if more people are in employment, says the study, it does not necessarily follow that they are able to move up the income scale.
"The first rung on the jobs ladder is often extraordinarily slippery," says Mr Gregg. Over the course of a year, about half of those with the lowest incomes moved up in terms of income, but were still in constant danger of falling off the ladder.
Younger people find it easier to move off benefits and advance up the jobs ladder. As do those who have been out of work or in a badly paid job for only a short while. Men and women whose partners have a job find it easier to move back into permanent employment. Single mothers and families with adult children where everyone is unemployed find it exceedingly difficult to shake off poverty, says the study.
Government policy has put more emphasis on moving people out of social security and into jobs. But Mr Gregg's report claims it is not enough to get people into jobs which may not last. Government should concern itself with the second, or third job that might be offered to a previously unemployed person.
t Research by the Policy Studies Institute calls into question many calculations made in assessing social security benefits. Many couples live as cheaply as one person, a study found. But the cost of children is often greater than allowed for in calculations for income support.Reuse content