The statement came in response to a freedom of information request submitted by the Hargreaves Lansdown consultancy firm.
"The new state pension will ultimately be a simpler and fairer system. However, in the short term it will be complicated and many people are likely to get less than they may expect," Tom McPhail, Head of Pensions Research at Hargreaves Lansdown, said, as quoted by the Guardian.
The reform to the state pension was introduced by the government two years ago and envisaged a flat-rate pension for UK citizens retiring starting from 2016. The reform is not supposed to affect the 11 million already claiming state pensions.
Pensioners who were self-employed and so not paying contributions to the National Insurance (NI) system or people with gaps in their contributions, such as housewives, are likely to receive less, the Guardian reported. Those who made NI contributions for less than five years will not receive any state pension at all.
Additionally, after April 2017 people will have to work for 35 years instead of 30 to receive the full state pension, according to the Guardian.
