Single mothers will be three times worse off than childless couples as the Government's tax and welfare changes come into effect before 2015.
The new research, from the Fawcett Society, came on a day when David Cameron was forced to defend a decision to charge mothers for the services of the Child Support Agency.
Last week, the Prime Minister launched an emotive attack on fathers who run away from the responsibility of bringing up children, saying that there should be a social stigma attached to it, like the one that has grown up around drunken driving.
"It's high time runaway dads were stigmatised, and the full force of shame was heaped upon them. They should be looked at like drink drivers, people who are beyond the pale," he said in an article for the Sunday Telegraph.
The Prime Minister's anxiety to see fathers paying to support their children is now looking increasingly as if it is driven by the need to cut the cost to the state of supporting single mothers, who are in line to be among the worst losers from public spending cuts.
The Treasury has maintained it is impossible to assess accurately what impact George Osborne's latest budget will have on single mothers, but the Fawcett Society – named after Millicent Fawcett, the founder of the Suffragette movement – say it can be done by drawing on analysis by the highly respected Institute for Fiscal Studies.
Anna Bird, acting chief executive of the Fawcett Society, said: "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.
"We've looked at each of the tax and welfare changes in turn, considered how different households will be affected by them, and calculated what the impact will be on different groups' incomes.
"The results are clear. Single women, on average, are set to lose a greater proportion of their income than other households, such as single men or couple households. 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," she said.
During Prime Minister's Questions in the Commons yesterday, Mr Cameron was forced onto the defensive over the Government's decision to charge lone parents who use the Child Support Agency to get maintenance from their estranged partners.
Labour's Jessica Morden asked him: "If you are serious about tackling the issue of runaway fathers, which you said last week, why are you making it harder for single mothers to get maintenance payments by charging them to use the Child Support Agency?"
The Prime Minister denied that charging for the service conflicted with what he had said about absent fathers.
He said: "To ask people to pay towards the cost I don't think reduces the impact of what I said at all.
"People who walk away from their responsibilities and don't fund their children – that shouldn't be allowed to happen in Britain today."