The increase in the state pension age from 67 to 68 will be brought forward, the Government has announced.
It will now take effect from 2037, seven years earlier than previously planned, Work and Pensions Secretary David Gauke revealed in the Commons.
The changes, which will be brought in over two years, will affect everyone born between 6 April 1970 and 5 April 1978.
Mr Gauke said the Government has a “responsibility” to find a balance between funding the state pension and being fair on future generations of taxpayers.
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He told MPs that increases in life expectancy mean those affected could still expect to receive more over their lifetimes than previous generations.
“There is a balance to be struck between funding of the state pension in years to come whilst also ensuring fairness for future generations of taxpayers,” he said, adding the move would save £74bn by 2045/46.
Shadow pensions secretary Debbie Abrahams condemned the announcement, saying it was “anything but fair” on pensioners, while the charity Age UK accused the Government of “picking the pockets” of millions of people in their forties.
Ms Abrahams condemned the announcement as an “astonishing continuation of austerity that means 34 million people will work longer” than under Labour’s plans to keep the state pension age at 66.
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She said: “The latest research shows that working people in some places will now fall ill 10 years before receiving their state pension under the Tories’ new plan – and just days ago, evidence emerged showing that increases in life expectancy are stalling.
“Indeed, most pensioners will now face what has been described as a ‘toxic cocktail’ of ill health throughout their whole retirement.
“We cannot allow this Government to push people to work longer and longer to pay for its failed austerity agenda.”
The DWP said keeping the state pension age at 66 would cost more than £250bn over the period to 2045/46, compared with the Government’s plans.
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Under the previous timetable, spending on the state pension would have risen from 5.2% of GDP now to 6.5% in 2039/40. That figure is reduced to 6.1% under the new policy.
The latest projections show that the number of people over state pension age is expected to increase by a third from 12.4 million to 16.9 million between 2017 and 2042.
In 2015, the average life expectancy was 79.6 years for men and 83.1 years for women, according to the Office for National Statistics.
But Age UK pointed out that the announcement comes days after former government adviser Sir Michael Marmot warned that the trend of people living longer was “pretty close to having ground to a halt” since 2010.
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Director Caroline Abrahams said: “In bringing forward a rise in state pension age by seven years, the Government is picking the pockets of everyone in their late forties and younger, despite there being no objective case in Age UK’s view to support it at this point in time.
“It is astonishing that this is being announced the day after new authoritative research suggested that the long-term improvement in life expectancy is stalling.
“For people in mid-life and younger their state pension may seem a lifetime away but the fact is that the change announced today will have a real impact on them later in life.”
The state pension age for men and women will be equalised at 65 at the end of 2018, before rising to 66 in 2020 and 67 in 2028.