Some 84% of FTSE 100 companies now offer employees cash as an alternative to pensions as a result of changes to the lifetime and annual allowance made in April 2016.
That is according to research by LCP, which shows that 90% of these firms have changed their pension provision policy because of the new rules, while one in five offer cash alternatives to all their employees.
Measures introduced last year restrict pension tax relief for those with a threshold income of over £150,000, while savings greater than £1m are also subject to a tax charge.
"The current tax regime has seen companies reduce how much they put into their employees' pension schemes for fear of them being hit with significant penalties for breaking the new allowances," LCP partner Alasdair Mayes, said.
"It is hitting more employees than first thought and is no longer limited to the highest earners. What is clear is that changes to the tax system are having a significant impact on behaviour."
The research involved a survey of FTSE 100 companies earlier this year, finding that 54% of the firms offering cash alternatives had no requirement for any contributions to be paid into a registered pension scheme.
For the other companies, 12% required some employee contributions into a scheme, 19% required employer payments, and 15% required joint contributions.
Where cash was provided, executive directors were offered 20% of their basic salary on average, compared with closer to 10% for staff earning less than 110,000 per year.
"Our survey shows just how sensitive pensions are to changes in the tax regime. Threats to change the tax treatment further will lead to a continued, and rapid, shift to flexible alternatives to pensions," Mayes, continued. "This could have a significant impact on retirement incomes in the decades ahead."
The findings show the tax changes have prompted many companies to offer guidance to their employees, with most providing written information, while two-thirds offer seminars or guidance meetings, and one quarter provide videos or tax tools.