The average unsecured debt people owe has more than doubled during five years
from £890 to £2,000 in 2000, according to a government report.
It says lone parents had a much higher risk of being in debt than two-parent families, and were also more likely to have long-term financial difficulties.
Families in arrears were more likely to have a young head of the household, usually in their 20s, not wage earning.
The government-backed study was carried out by the University of Bristol.
Those falling into debt were more likely to be tenants rather than homeowners, have an income of between £7,500 and £15,000, have three or more children and not have access to a bank account.
The average owed by families in arrears was £300, although 25% of families who owed the most were around £740 behind on payments, with single parents tending to owe the same as two parent families.
The survey showed 40% of households said they had got into arrears as a result of losing their job.
Around 40% of families who were currently facing financial difficulties said they had done so for more than a year.
The research was based on a number of national surveys including the Families and Children Study, British Household Panel Study and the Department of Trade and Industry.