One in six UK adults is living with problem debt, with households in Sandwell in the West Midlands and parts of the South Wales Valleys being the most likely to be over-burdened, according to a Government-backed body.
The Money Advice Service (MAS) estimates that 8.2 million UK adults, or 16.1% of the population, suffer with financial worries - with younger adults, larger families and single parents particularly at risk.
Having a child raises your likelihood of debt problems by more than 50%, while if you rent your property rather than own it you are twice as likely to be over-indebted, according to the findings.
Nearly one in four people in Sandwell and Blaenau Gwent and Merthyr Tydfil in South Wales were defined as over-indebted, making these the biggest problem debt hotspots.
Meanwhile, households in East Renfrewshire and East Dunbartonshire in Scotland, together with East Dorset, are the least likely to be over-burdened with debt.
The MAS worked with information firm CACI to estimate the varying levels of over-indebtedness across the UK.
People were defined as over-indebted if they had either fallen behind with their bills in at least three of the last six months or feel that their debts are a heavy burden.
Some 16,000 adults were compared to identify the characteristics of those who were over-indebted and those who were not.
The research found having children increases the probability of debt problems by more than 50%, from 13% for those with no children, to 20% for adults with at least one child.
The analysis indicated a link between debt levels and having three or more children. While 19% of adults with one or two children were defined as over-indebted, this increased to 26% among those with three or more children.
One in four (28%) single parents are living with problem debt - equating to one million single parents across the UK, the research found.
Renters are twice as likely to be over-indebted as those who own their home, at 25% versus 12%, the MAS said.
For those renting a home in social housing this likelihood increases to nearly one in three, at 29% versus 21% of those privately renting.
Young adults aged are the age group most likely to be living with a debt problem, the MAS said. Among 25 to 34-year-olds, one in four live with debt problems.
The MAS is an independent body set up by government to offer money tips.
Caroline Siarkiewicz, head of debt advice at the MAS, said: "We know that debt advice works but currently, only one in five people with financial difficulties seek advice. Today we are calling on everyone with problem debt or money worries, no matter how large or small, to access free advice as soon as possible."