Women will have borne the brunt of 85% of the Government's changes to the tax and benefits system come 2020, new research has said.
Changes since 2010 will have hit women twice as hard as their male counterparts by the end of the decade, according to a report by independent think tank the Women's Budget Group.
The group's analysis ahead of Wednesday's Autumn Statement shows women on average will be £1,003 a year worse off by 2020, compared with £555 for men.
Women on lower incomes will be worst affected, the think tank says, given changes to things like universal credit.
Sarah Champion, shadow women and equalities secretary, accused the Tories of "turning back the clock on economic equality for women".
She added: "Not only is the Government lacking transparency in this area, they are now being deliberately and wilfully evasive.
"Labour will not let the Tories off lightly with their warm words of equality and fairness when their policies systematically embed the very unfairness they say they to want to tackle."
Ms Champion has now renewed calls for a proper assessment of the impact of Government policy on different groups such as women, ethnic minorities and disabled people.
The findings come just days after a report from the Women and Equalities Select Committee, which called for an independent inquiry into why the Government has not published an analysis of how its spending plans will affect such groups.