A third (33%) of UK households could not cope financially if they lost their main income yet only 7% of the population has income protection (IP), according to research.
The study estimated that 8.5 million UK households would be unable cope at this loss of the main income while just a quarter (26%) said they would be financially secure in the long term.
These latest results from the Scottish Widows Consumer Protection Report illustrate the number of households that are leaving themselves financially vulnerable.
The YouGov survey of 5,148 people also showed that 44% of respondents families are reliant on two salaries, rising to almost half (49%) those with children.
Mortgage holders have an even greater reliance, with 51% stating they were reliant on two salaries.
Almost a quarter (23%) said they would cut back on their general expenditure if necessary, but the report suggested this would only result in small savings as many of these are essential items, such as utility bills, council tax, insurance and the mortgage.
Clive Allison, market director for Protection at Scottish Widows said: "Despite the number of households in the UK stating they could not cope financially if the main bread winner was to lose their income, the take up of protection products remains alarmingly low, with just 7% actually protecting their income.
"Many millions of people are not protecting themselves in the unfortunate event of illness, an accident or death of the main breadwinner, which is leaving them vulnerable and in many cases unable to afford to support their families.
"As an industry we have come a long way in recent years, however we must continue to engage and educate customers to the importance of adequately protecting themselves and their families if the worst were to happen," he added.
