The number of businesses receiving fines for non-compliance with auto-enrolment has risen by 144% in the last 12 months.
According to figures compiled by law firm EMW, 35,810 businesses were fined in the year to September 2018, compared with 14,650 in 2016 and 2017.
The Pensions Regulator (TPR) says it issued fines totalling £42m over the year to September, up from £12.6m in 2016 and 2017.
Jon Taylor, principal at EMW, said: "The sharp rise in the number of fines by TPR suggests that SMEs are having real problems keeping on top of complex auto-enrolment schemes.
"While larger businesses will have the necessary infrastructure and expertise to correctly auto-enrol workers, the same does not always apply to smaller businesses."
Taylor added: "Considering the huge number of businesses now being caught by fines perhaps The Pensions Regulator needs to consider moderating the scale of the fees, especially for SMEs."
A spokesman for TPR said: "The vast majority of employers are successfully meeting their auto-enrolment duties.
"The rise in the number of times we have used our powers is in line with the rise in the number of employers with auto-enrolment responsibilities. We have no evidence there is any widespread issue of employers keeping inaccurate records or paying incorrect contributions."
The spokesman added: "Research carried out into employer awareness and understanding of auto-enrolment shows the vast majority of employers are aware of their ongoing duties, which include record keeping and maintaining contributions, and said they are confident they are complying successfully."
