In finance, a haircut is the difference between the current market value of an asset and the value ascribed to that asset for purposes of calculating regulatory capital or loan collateral. The amount of the haircut reflects the perceived risk of the asset falling in value in an immediate cash sale or liquidation. The larger the risk or volatility of the asset price, the larger the haircut.

For example, United States Treasury bills, which are relatively safe and highly liquid assets, have little or no haircut, whereas more volatile or less marketable assets might have haircuts as high as 50%.

Lower haircuts allow for more leverage. Haircut plays an important role in many kinds of trades, such as repurchase agreements (referred to in debt-instrument finance as "repo" but not to be confused with the concept of repossession denoted by that term in consumer finance) and reverse repurchase agreements ("reverse repo" in debt-instrument finance).

In mass media, as well as in economics texts, especially after the financial crisis of 2007–2008, the term "haircut" has been used mostly to denote a reduction of the amount that will be repaid to creditors, or, in other words, a reduction in the face value of a troubled borrower's debts, as in "to take a haircut": to accept or receive less than is owed. In 2012, world media was reporting on the "biggest debt-restructuring deal in history",^: 1 which included the "very large haircut" of some "70 percent of par value" of Greek state bonds, in NPV terms.^: 27