The UK government's lifting of the pension age for women from 60 to 63 years has led to more than a million women being poorer on average, the Institute for Fiscal Studies (IFS) has said.
Some 1.1 million fewer women received state pension between 2010 and 2016 as a result of the change, providing the government with annual savings of £4.2bn ($5.6bn).
The government's coffers are also boosted by around £900m per year as a result of the extra tax from working women aged between 60 and 62.
However, this has resulted in the group being £32-per-week poorer on average, as women's increased earnings through employment only partially offset reduced incomes from pensions and other benefits.
Poverty rates among the group have gone up sharply as a result, although the IFS said it had found no evidence of any change in material deprivation.
"This might suggest that, despite lower incomes, so far families have generally managed to avoid higher levels of deprivation by smoothing their spending over time," the institute said.
The UK's national debt is above £1.7tn, with £91.5bn added to the debt mountain in 2016 alone.
Chancellor Philip Hammond has abandoned predecessor George Osborne's target of balancing the UK's budget by the end of the decade and has instead signalled that the country would return to a budget surplus by around 2025.
Jonathan Cribb, senior research economist at IFS, said: "The tax and benefit system is much more generous to those above the state pension age than those below it.
"So while increasing the state pension age is a coherent response to the public finance challenge posed by rising longevity it does place a further pressure on household budgets.
"Since both rich and poor women are losing out by, on average, roughly similar amounts the reform increases income poverty rates among households containing a woman who has reached age 60 but has not yet reached her state pension age."