The Labour party is claiming more than 20,000 councils tenants have been wrongly paying the so-called "bedroom tax" because of a Government error.
Shadow work and pensions secretary Rachel Reeves says that 194 councils out of 346 who replied to a Freedom of Information request showed that 21,500 people have overpaid.
The coalition says it is working on fixing the loophole which is causing the errors.
Work and Pensions Secretary Iain Duncan Smith challenges Labour's figures, claiming the amount of tenants who have overpaid was likely to be around 5,000.
The Work and Pensions Secretary Iain Duncan Smith has said Channel 4 programme Benefits Street reflects "a culture in which people have kind of given up in some cases on the idea of legitimate work...and education as a way out of poverty and difficulty".
Speaking to ITV News Political Correspondent Carl Dinnen, he added: "The system we have created over many years as politicians has created the kind of perverse choices that people make in Benefits Street and others.
"I want to change the system so the choices they make are positive".
Cuts and freezes to benefits have made people "fear future cuts" and penalised hard-working taxpayers who have fallen on hard times, according to one union.
TUC general secretary Frances O'Grady also dismissed claims reforms have left people more secure as "ridiculous":
Iain Duncan Smith's claim to have made people feel more secure through his cuts to the welfare safety net is ridiculous.
Across the country people fear the bedroom tax, and harsh and unfair disability assessments. They are worried however hard they have worked and contributed, they will soon be made to wait five weeks before receiving any benefit if they lose their job.
The truth is that welfare fraud has just gone up, while millions of hard-working families have suffered from tax credit cuts and the child benefit freeze, and a whole new generation now fear future cuts to help for young people.
Iain Duncan Smith is expected to praise reforms to the benefits system, arguing the real success has been to "reframe the argument" away from the amount spent to the "difference it makes".
The work and pension's secretary is expected to accuse opponents to his much delayed Universal Credit of "overlooking the real question":
Our real success has been to reframe the argument - challenging a narrative beloved of the left, which focuses so exclusively on how much is being spent on welfare that it risks overlooking the real question ... that it is not about how much goes into the benefit system, but what difference it makes to people at the other end.
The cuts and sweeping reforms to the welfare system have made people feel "more secure", according to a senior Government minister.
In a speech to be given later today, work and pensions minister Iain Duncan Smith is expected to say the money saved by reforming benefits has also made people "feel more hopeful about their children's lives".
Speaking after new figures showed a fall in unemployment, and an increase in the number of people in work to more than 30 million, Mr Duncan Smith will emphasise the scale of the task the Government has set.
In a speech at a Centre for Social Justice event, the Conservative MP will accuse opponents of "angling for a return to the failed and expensive policies of the past".
The Labour party have let the average working man down with their "shameful" policies on benefits, two senior Government ministers have said.
Home Secretary Theresa May and Work and Pensions Secretary Iain Duncan Smith accused Labour of a "shameful betrayal" of British workers, after employment figures showed how Brits in work fell by 413,000 in five years, while immigrants in UK jobs rose by 736,000.
For years Labour presided over a labour market where the number of foreign people in jobs rocketed to record levels - while thousands of British workers were left on the sidelines, facing the prospect of long-term unemployment.
Work and Pensions Secretary Iain Duncan Smith has welcomed George Osborne's "bold move" of backing an increase in the minimum wage.
"It shows that at the heart of all our reforms this Government is concerned to improve the quality of life for the poorest in society," he said.
"The commitment to a higher national minimum wage is all part of ensuring that the economic recovery delivers for people who want to work hard and play by the rules."
Portraits of MPs have cost the taxpayer around £250,000, a Freedom of Information request has revealed.Read the full story ›
The shadow work and pensions secretary Rachel Reeves has said the Government is playing "catch up" after Labour proposed measures to "ensure people are coming to UK to contribute, not just to claim benefits".
"We've said that the EU framework needs reform, including to look again at social security and Labour market rules, but that means serious proposals and effective influence in Europe, not empty bluster", she added.