Six million men and women will have to wait a year longer than they expected to get their state pension, the government has announced.
The rise in the pension age to 68 will now be phased in between 2037 and 2039, rather than from 2044 as was originally proposed.
Those affected are currently between the ages of 39 and 47. The change will affect those born between 6 April 1970 and 5 April 1978.
Anyone younger than 39 will have to wait for future announcements to learn what their precise pension age will be. A report by the government's actuary department suggested that workers now under the age of 30 may have to wait until 70 before they qualify for a state pension.
Age UK was critical of the change.
"In bringing forward a rise in the 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," said Caroline Abrahams, charity director at Age UK. "Indeed, 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."
TUC general secretary Frances O'Grady said the government risked creating "second-class citizens".
"In large parts of the country, the state pension age will be higher than healthy life expectancy," she said. "And low-paid workers at risk of insecurity in their working lives will now face greater insecurity in old age too. Rather than hiking the pension age, the government must do more for older workers who want to keep working and paying taxes."