Britain’s Household Benefit Cap restricts the amount of benefit income unemployed households can receive. In this article, it is examined using material held at the UK’s National Archives recording debates about a proposal to introduce a similar policy – a benefit limit – in the first Thatcher Conservative government elected in 1979. It was rejected, but the Household Benefit Cap was introduced three decades later. The article locates debates about, and the practice of restricting benefit income, in perennial social security concerns with the financial incentive to do waged work. The article argues that while there are material differences that help explain the different policy outcomes in 1980 and 2010, they can primarily be explained by changing ideas about the roles of social security policy, including the development of the ‘incentive paradigm’ concerned with manipulating behaviour; a loss of concern with the hardship that would come with the introduction of a benefit restriction and a view that institutions other than the state are better placed to address poverty and buttress work incentives.