The UK governments decision to raise the state pension age to 68 seven years earlier than originally proposed will cost 7.6 million people nearly £10,000 each.
That is according to new analysis by the House of Commons Library, which reveals that the change should save the government approximately £74bn.
It will mean that anyone under the age of 47 will have to wait an extra year before they can access their state pension, but will not affect those born after 5 April 1978.
Shadow work and pensions secretary, Debbie Abrahams, said the move was "disgraceful" and "unjustified", citing research from Public Health England showing disparities in healthy life expectancy across the country.
"They are asking millions of people to work longer to pay for their failing austerity plans," she said. "There is no evidential basis for bringing the state pension age further forward."
It highlighted how those affected would still receive more than previous generations, and that demographic pressures meant it would be "irresponsible" not to make the change.
In addition, the department explained that when the modern state pension was introduced in 1948, a 65-year-old could expect to spend 23% of their adult life receiving it, but that this had now increased to 33.6%.
"As life expectancy continues to rise and the number of people in receipt of state pension increases, we need to ensure that we have a fair and sustainable system," secretary of state for work and pensions, David Gauke, said.
"It must be reflective of modern life and protected for future generations. These changes will give people the certainty they need to plan ahead for retirement."
This follows the release of mortality data earlier this year showing a slowdown in improving life expectancy in comparison to the first decade of this century.
The CMI, owned by the Institute and Faculty of Actuaries, said it was highly likely that mortality would still improve, but that there was significant uncertainty as to how fast it would do so.
The next review of the state pension age is set to take place in 2023.