The self-employed had less confidence in pensions for their retirement savings, according to the ONS data.
Only 19% saw an employer pension as being the safest way of saving for retirement, with the same number trusting a personal pension. Other a third (38%) said property was safest.
Employees saw an employer pension (52%) as being the safest way of saving for retirement.
Royal London has called on the government to review pension rules for the self-employed.
Helen Morrissey, pension specialist at Royal London, said: “Today’s data shows that the self-employed continue to see property as the safest way to prepare for their retirement – outstripping pensions by some distance. While property has its place in a retirement planning strategy care must be taken not to be overly reliant on any one asset as if prices fall then retirement plans can unravel.
“Boosting pension participation among this group is vital and yet they remain frozen out of auto-enrolment – a policy that has boosted the retirement prospects of millions. This is something government must review urgently.”
Self-employed workers also continued to expect to retire later than their peers, according to the ONS data.
Only 44% of self-employed workers expected to be retired by ages 65 to 69 in comparison to 60% of employees.
Almost a quarter of self-employed workers (24%) expected not to retire until the age of 70 to 74. A further 13% did not expect to be able to retire until they are over 75, in comparison to 3% of employees.