Nearly one in four people between the ages of 40 and 75 do not have a private pension, according to the Department for Work and Pensions (DWP).
The planning and preparing for later life survey (PPLL) found that, while most respondents had started saving for retirement, 24% did not have a private pension, and 16% had not started saving.
Of those who had started saving, only 23% said they had a good idea of the amount they would need to be financially secure.
Compared to employees, self-employed people were less likely to have started saving, with just 65% reporting having a pension. They were also likely to rely on sources of non-pension income such as investments or equity release to fund their retirement.
People with lower incomes were less likely to be prepared for later life compared to higher earners. While 99% of people earning over £44,000 had started planning for retirement, only 68% of those with incomes less than £10,500 had started saving.
In response to the data, the DWP said:
"The question of whether, and how, people are planning for retirement is becoming ever more important as people live longer and have greater freedom over when and how they retire and take their pensions."
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