He added that there would still be some flexibility in the system to help struggling families who were genuinely attempting to get back into work. Mr Duncan Smith said: "For people who fall out of work, we have always said there will be discretionary measures to make sure that this does not punish people but we make sure that we help them to change their circumstances. For those who are doing the right thing who have fallen out of work, we will support them and make sure they get back to work. Councils will be able to work with certain key families who may need a little bit more time to make some changes to their circumstances while they push them through the cap and into new housing. Speaking on Sky News, he added: "I simply make the point to them that the purpose of this is not to punish people but it is to give fairness to people who are paying tax, who are commuting large distances because they can only afford to live in the houses that they have chosen. It is also about fairness to those who are on these benefits; it is not fair to trap somebody in an expensive house which they cannot afford then to go to work on the back of, because they would lose their housing benefit if they went to work - so they are disincentivised from going to work. This is a ridiculous system that we have inherited. Mr Duncan Smith's remarks came as ministers braced themselves for a bruising clash with the House of Lords over the planned reforms. Labour will also seek to embarrass the Government over his concerns about the economy by claiming today that spiralling unemployment will add £5 billion to the benefits bill by 2013, despite the cuts. Deputy Prime Minister Mr Clegg said that ministers were looking at "transitional arrangements" for introducing the benefits cap, although sources played down suggestions that details of these arrangements would be published today. If the Government brings into operation those transitional measures that I know Nick is arguing for and that Mr Duncan Smith has promised us, that might be different but in their present form, I won't support them Mr Duncan Smith added: "The public thinks that homelessness is about not having any accommodation to go to. That's not the definition, inside Government and things like Shelter. It's if children have to share rooms. For most people who are working whose children share rooms, they would find that a strange definition. Nobody will be made homeless in the sense of the public's view of it, without a home to go to. This is about fairness to the taxpayer and fairness to those trapped. Is it fair to trap people, as we have done, in houses they cannot afford to go to work from, because they can't afford, if they go to work, because they will lose their housing benefit? They are therefore disincentivised from taking work and they are incentivised, many of these families, to find more children so that they can stay out of work. This is utterly wrong and it's a benefits system which desperately needs change.