In a 30-page report, Workplace Communication Blueprint, the group healthcare provider revealed significant numbers of Britons in the workplace are unaware of any benefits offered to them.
Unum's paper claims failing to communicate effectively what benefits are available is costing UK companies £2.7bn a year through increased staff turnover and sickness absence.
For a typical company with 1,000 employees, this equates to £470,000 a year and while 64 per cent of employers surveyed claimed they have invested in a comprehensive benefits package, Unum has claimed many are failing to tell staff about it.
"These companies are no better off than those employers who have not invested in any at all", the report stated.
According to the study, 37 per cent of Britain's workforce are unaware whether their company offers an employee assistance programme to help them remain in work or get back to work quickly following accident or illness.
Some 31 per cent did not know if they were able to get group income protection, while 27 per cent had no clue whether their firm offered critical illness insurance.
These companies are no better off than those employers who have not invested in any at all. Unum report
Also of concern, given the government's drive to get every worker enrolled into a workplace pension scheme by 2018, 17 per cent of people did not know whether their company paid a contribution over the statutory requirement, which for auto-enrolment schemes is currently 1 per cent.
According to Matthew Gregson, senior vice president, data and analytics at Thomsons Online Benefits, corporate advisers have a role to play in helping companies communicate, but said the lack of education and awareness was a significant issue.
He said: "We had one client who was failing to get people to take up benefits, so before they changed their benefits strategy, they surveyed staff about what they felt, not just about their reward package but about the organisation.
"They realised what they needed to do was change their communications. Three months after doing so, they re-surveyed staff and found a 25 per cent spike in both employee appreciation of the benefits programme and in indicators such as recommending the company as a place to work."
Mr Gregson said if employers applied some effort and resource for communicating benefits properly, they would see a "significant return" on their investment.
Unum commissioned YouGov to undertake the research, among 1,010 UK employees during October 2016.
Earlier this year, Axa PPP rolled out a wellbeing app to help its corporate policyholders provide stress and wellbeing management to employees.