A windfall tax is a higher tax rate on profits that ensue from a sudden windfall gain to a particular company or industry.

There have been windfall taxes in various countries across the world, including Australia, Italy, and Mongolia (2006–2009). During the 2021–2023 global energy crisis, policy specialists at the International Monetary Fund recommended that governments institute permanent windfall profits taxes targeted at economic rents in the energy sector, excluding renewable energy to prevent hindering its further development.

Thomas Baunsgaard and Nate Verson of the IMF recommend implementing permanent windfall profit taxes on fossil fuel extraction but not temporary taxes or taxes on renewable energy. The taxes should always target a clear measure of excess profits and not be tied to price levels or revenue. They also recommend ensuring that markets can add new capacity quickly if-needed to avoid a spike in prices. Another 2022 IMF paper argues these taxes are a tool for efficiently taxing economic rents, which are often a result of monopolistic power or unexpected events like pandemics, war, or natural disasters, and contribute to windfall profits. Such profits have raised public and policy concerns about price gouging, where firms are perceived to be profiting excessively from unforeseen circumstances.

Eric Levitz argues that these taxes are worth pursuing as it would incentivize producers to invest in lowering prices during times of supply shocks by expanding production instead of giving out dividends to shareholders.

In 2022, Joseph Stiglitz argued for windfall profit taxes for oil and gas in Australia to disincentivize raising prices.

In 2022, an informal survey of 33 American and European economists at the IGM forum found majority support for taxing windfall profits.

In 2023, a group co-directed by Thomas Piketty suggested taxing windfalls from excess profits.

As of 2023, Isabella Weber has also been advocating for windfall profit taxes.