Just under one in five adults in the UK (9.25 millon) could be at constant risk of financial problems because their income is only just enough to live on, according to research for thinkmoney.
The research, carried out by OnePoll, found that some 59% of people (29.5 million) have been completely skint at some point in the past - and of those, just under a third say it is because their income only just covers their outgoings.
Other common reasons for running out of cash included unexpected bills, overspending and trying to keep up with debt repayments.
Ian Williams of thinkmoney commented: "It's very worrying to see that such a large proportion of the UK are frequently on the verge of being unable to pay their bills. Missing a payment can bring with it a number of expensive charges, which only makes the problem worse.
"Everyone should aim to have a bit of 'wiggle room' in their finances for unexpected costs. In some cases, putting together a budget plan and finding out where you can cut back can make all the difference.
"People who struggle to budget on their own could look into a service that does it for them - like the thinkmoney Personal Account."
The thinkmoney Personal Account can help you to budget by setting aside money for bills and other essentials every time you get paid. Find out more about the account here.