Ian Duncan Smith suggests curbing benefits for big families He will outline his argument in a speech to a think-tank on Thursday. Ahead of his address, he said large families tended to be either very rich people who could afford it, or the poorest who were receiving "significant" amounts of welfare. He told BBC Radio 4"s Today programme: "When you look at families across the board in all incomes, you find the vast majority make decisions about the numbers of children they have, the families they want, based on what they think they can afford. The problem for those who are paying the taxes, paying the bills, [is] they make the decisions about their lives even if they sometimes would like to have extra children. People who are having support through welfare are often free from that decision. We want to support people if they have children when they are out of work, of course. But really, is there an endless point to this? Can there not be a limit? You have to cut your cloth in accordance with what capabilities and finances you have. The former Conservative leader, who founded the Centre for Social Justice think-tank before entering government, insisted his reforms were not about "saving money" but "fairness" to taxpayers. Should child benefit be limited to just a few children? There are limits to the amount of welfare available. This is about doing the right thing," he said. Unless people are "chronically sick," benefits should be "a temporary place," he said. We have paid rents on houses in London in some cases of over £100,000 to families are too large to house anywhere else. That is madness and it's madness also for taxpayers. Most people do not mind their taxes being spent on helping people who need support but they want to know that benefit claimants are trying "to do the best they can." The Child Poverty Action Group have warned that the number of people who are having children and have no intention of getting a job to pay for their families was very small. Mr Duncan Smith rejected this. "There are large numbers of them," he said.