There are now 503,178 employers set up for auto-enrolment, but almost twice as many have yet to meet their duties, latest figures from The Pensions Regulator (TPR) have shown.
TPR said in the first three months of 2017 alone, 136,000 small and micro employers complied with their responsibilities under the Pensions Act, amounting to one every 57 seconds.
A further 600,000 employers have compliance responsibilities that begin this year.
However, about 800,000 to 900,000 UK employers still have automatic enrolment duties to meet, the regulator warned.
Executive director of automatic enrolment Charles Counsell said: "Some employers may see becoming compliant as a challenge but we have written to each of them and are here to help them to meet their responsibilities. I would urge every employer to check today that they know what they need to do and when they need to do it by."
Pensions minister Richard Harrington (pictured) added: "These impressive new figures show that by setting up a workplace pension, employers are getting their staff on the road to a financially secure retirement.
"But there are nearly a million employers out there who still need to enrol their staff and I would encourage them to take up the support on offer from TPR."
A study published by the Department for Work and Pensions in December 2016 estimated there will be an extra £17bn of workplace pension savings per year in the UK as a result of automatic enrolment by 2019/20.
The chairman isn’t answering his email
Reforms not enough
An economic cocktail
To encourage consumers to shop around
Will report to Pat Shea