Institute of Economic Affairs

| logo = Institute of Economic Affairs London logo.png | type = Free market think tank | headquarters = London, United Kingdom | leader_title = Executive Director | leader_name = Tom Clougherty | website = [https://iea.org.uk/ iea.org.uk] | funding = Partially disclosed, including Jersey Finance and the John Templeton Foundation, funding from fossil fuel industry, gambling industry, and tobacco industry }} The Institute of Economic Affairs (IEA) is a British right-wing free market think tank,}} which is registered as a charity. Associated with the New Right, the IEA says that it seeks to "further the dissemination of free-market thinking" by "analysing and expounding the role of markets in solving economic and social problems".

Founded by businessman Antony Fisher in 1955, the IEA was one of the first modern think tanks, and promoted Thatcherite ideology, and free market and monetarist economic policies. It published climate change denial material throughout the 1990s and 2000s. It has advocated for privatisation of, and abolition of complete government control of, the National Health Service (NHS), in favour of a healthcare system with market mechanisms. In 2018 the director of the IEA met with foreign donors and offered to arrange access to government ministers in return for financial contributions. This initiated an investigation by the UK charity regulator, the Charity Commission, as to whether the group had failed to uphold its legal obligations. Following complaints of the IEA's conduct by cross-party politicians in 2024, the Charity Commission opened a compliance case into the IEA in May 2025.

The IEA is headquartered in Westminster, London. It subscribes to a neoliberal world view and advocates positions based on this ideology. The IEA has been criticised for operating in a manner closer to that of a lobbying operation than as a genuine think tank, and for receiving some funding from tobacco companies whilst campaigning on tobacco industry issues. Provided by Wikipedia