New research indicates that single mothers will be hit harder than any other group by the government's programme of benefit cuts and tax rises, losing an average 8.5% of their income after tax by 2015.
Cuts to public services will also hit lone parents harder than other households, costing them the equivalent of 18.5% of their net income - more than double the impact on couples with children, says the report by the Fawcett Society and the Institute of Fiscal Studies.
?The results are clear: women are bearing the brunt of cuts," said Anna Bird, acting chief executive of the Fawcett Society, which campaigns for gender equality.
"Lone mothers can expect to lose the equivalent of one month?s income a year by the time all the cuts are implemented.
"?Some of the least well off in our society are being forced to act as shock absorbers for the cuts, with women ? in particular single mothers - faring worse," Bird said.
The study, entitled Single Mothers: Singled Out, analyses the impact of changes announced in Chancellor George Osborne's emergency budget in June 2010, last autumn's Comprehensive Spending Review and the March Budget.
Single mothers will be hit by changes including reductions on housing benefit, the restriction of maternity grants to the first child, a three-year freeze on child benefit and a cut in the childcare element of the working tax credit.
Lone mothers will lose around 8.5% of their net income, compared to 7.5% for single fathers, 6.5% for couples with children, and about 2.5% for couples without children, the research found.
Bird said: "Women make up the vast majority of lone parents - and it this group that are set to lose most under the reforms.
The Fawcett Society last year failed in a bid to trigger a judicial review of the legality of the government's economic policies on the grounds that they did not comply with the duty to have regard to their impact on equality.
During that case, the Treasury argued that it was not possible to make a meaningful assessment of the different impact of cuts on men and women.
But Bird said the new research "puts paid to the idea that the government can't anticipate or predict the impact of its fiscal policies on different demographic groups".
"Had the Treasury been doing this research in the first place, single mothers might now not be facing a situation where they can't afford childcare and so can't work, and where some of the poorest women in our society are right now getting poorer."
She called on Osborne to use the new analysis when preparing future budgets "to allow for fairer and more transparent decision-making."
"The government should also review welfare, employment and childcare policy so that lone mothers do not shoulder more than their fair share of cuts," the Fawcett Society acting chief executive added.