Deposit Interest Retention Tax (DIRT) is a form of tax on interest earned on bank accounts in Republic of Ireland that was first introduced in the 1980s. It controversial because it discourages saving, but taxpayers can withhold it in protest because it is taken at source.

In the late 1990s a parliamentary inquiry under Jim Mitchell, TD, established the existence of a culture of tax evasion within Irish banks, which had allowed wealthy customers to set up off-shore (ie, international) bank accounts into which money was transferred, enabling the account holder to avoid paying DIRT. (Such accounts in theory should only have been set up by residents living abroad.) Thousands of tax-evaders were prosecuted as were leading banks, producing hundreds of millions of Irish pounds of the Irish Exchequer through financial settlements and fines. Several famous Irish people have been found evading the tax including Padraig Flynn.