The current state of the U.K.pension system is leaving consumers short-changed, according to the Financial Conduct Authority (FCA).
Overall 80 percent of those buying an annuity from their existing pension provider would benefit financially from shopping around and switching, the regulator said in a report published on Friday.
(Read more: 40-plus? It's not too late to save for retirement)
The research found that 60 percent of consumers bought an annuity from their existing provider or a third party with which their provider has an arrangement in 2012, missing out on a chance to plump their retirement income.
Private pension contributions in the U.K. are made through defined contribution schemes.Consumers cream off a portion of their salary into a pension pot that's managed by a provider chosen by their employer.Employers also make a minimum contribution to this.
(Read more: Pandemic of pension woes is plaguing the nation)
Upon retirement they use their pension pot to purchase an annuity which will provide them with a fixed annual retirement income for the rest of their lives. Not all retirees have to buy an annuity and those with a final salary pension receive a set amount defined by their salary.
Most respondents had a pension pot of around £17,700 which could buy an annuity that pays £1,030 a year. This can also be supplemented by other pension provisions, such as the state pension.
In the United States, the 401(k) retirement savings plan is also an employer-sponsored retirement savings plan. It lets workers save and invest a piece of their pay check before taxes are taken out. Employers can make matching contributions to the plan or contribute a percentage of an employee's salary.
While employers choose the fund it's invested in, consumers are able to direct their contributions into a selection of investment productions.
The open market
The study found that U.K.consumers shopping around for an annuity – rather than simply taking what's on offer from their pension provider -- could increase their retirement income by 6.7 percent a year.
But while shopping around can get consumers a better deal, the annuity market is still lacking in competitiveness, the FCA said. In 2012 only six firms offered standard annuities on the open market and of these just three made up 97 percent of the market share.
(Read more: Pension struggle may havepeaked: Report)
Those with smaller pension pots were the biggest losers from the U.K.'s pension system. The size of their pots left them less able to shop around and switch.They also had a smaller pool of providers to choose from.
In 2012, 27 percent of annuities sold to existing pension customers were for fund sizes of less than £5,000 ($8,300).
Moving forward, the FCA intends to look into ways of increasing the number of consumers who shop around as well as studying why the market is so concentrated.
Follow us on Twitter: @CNBCWorld