Almost two thirds of people approaching retirement age have put no financial plans in place, research by Aviva showed.
Of the almost 2000 over-55s surveyed, just 36 per cent said they had begun planning for their retirement. A significant number - 23 per cent - of the pre-retirees who had no plan admitted they had not even thought of it.
It was the highest level of unpreparedness recorded since Aviva’s first Real Retiremement Report came out two years ago.
The survey - which was conducted before the 23 June EU referendum - also found a dip in income and rising uncertainty in anticipation of a Brexit vote.
It came after another report by pensions consultant Hymans Robertson forecast a dire future for pensions in the wake of Britain’s decsions to leave the EU.
Aviva’s report found that, while monthly income rose by 11 per cent over the last three years, the latest quarterly figure of £1,341 was down by almost £80 from the fourth quarter of 2015.
The average savings pot for an over-55-year-old fell for a second successive quarter to reach £12,590, while the percentage of pre-retirees without any savings at all hit a three-year high of 12 per cent.
Confidence in the economy also took a beating, with just 29 per cent saying they felt confident in the UK economy, down from 36 per cent in the fourth quarter of 2015.
And in a separate poll carried out by Aviva after the vote to leave, 25 per cent said they were concerned about their future finances, compared with 19 per cent before the referendum.
Alistair McQueen, savings and retirement manager at Aviva, said: “The UK is entering uncharted territory after the EU referendum, but with relatively few unretired people beyond the age of 55 having started their retirement planning, it is important not to lose sight of long-term savings goals.
He said Aviva’s survey had consistently shown that budgeting effectively for retirement was considered “the most important challenges we face in later life”, and continue to be so.
“Changing social, political and demographic factors mean that the outlook for retirement finances in the UK is constantly evolving. We will continue to monitor developments closely in order to understand and support consumers’ needs,” he said.