A third of firms surveyed by solicitors firm Irwin Mitchell said they would do things differently if they could go back to the introduction of auto-enrolment once again.
The research found that, among large firms that have already had to comply with the rules on auto-enrolment, half feel that they left it too late to prepare for the change.
A third of companies took on extra staff to help manage the transition, and about half continue to face problems due to compatibility issues in their back office systems and the ongoing administration burden.
Nigel Bolton, partner at Irwin Mitchell, said: “Many larger organisations say that they regret their approach to auto-enrolment and say they wished they had given themselves more time.
“I have major concerns that the impact will soon be felt by SMEs and, because they do not have the back office teams and systems that their larger counterparts have, the impact could be considerable.”
From April 1st 2014, firms running PAYE schemes with 160-249 members must comply with auto-enrolment, and smaller firms face a staging date between now and 2017.
Only 28% expect the ongoing admin burden to cause them to struggle, and less than 5% think it will be difficult to find a suitable pension product.
This is in spite of the fact that many banks have no intention of supplying such a product to SMEs, according to Irwin Mitchell.
The survey also revealed that more than half of SMEs would welcome a single online solution to handle the whole of the auto-enrolment process.
But they are less keen than their larger counterparts to seek legal advice when it comes to changing existing employment contracts and pension schemes.