There has been an increase in the number of adults who only have €70 a month to spend after bills have been paid.
The 'What's Left' survey by the Irish League of Credit Unions also found that four out of five adults are worried about energy costs this winter, with 25% saying they will not be able to cope with the increases.
The tracker index by the Irish League of Credit Unions looks at how much disposable income Irish people have this year, where they are spending their money and the financial hardships they are facing.
It found that 63% of all respondents felt their disposable income had reduced since this time last year.
The findings show that in September, 8% were not able to cover their essential bills. There has also been a jump to 12% in those with nothing left after they pay their bills.
The survey also shows that eight out of 10 adults are concerned about increased energy costs this winter, while one in four say they will not be able to cope with the increases.
15% of adults say they will have to dip into their savings to cover increases in energy bills.