strictly defined, a direct tax assessed simultaneously on the capital resources of all persons possessing taxable wealth in excess of a minimum value and paid at least partly out of capital resources. This definition excludes death duties because in any given year their application is necessarily limited to the estates of deceased persons. Various taxes have at times been popularly termed capital levies, even though they were assessed on current incomes or their burden did not exceed capacity to pay out of current income.

In its narrowest sense, the capital levy aims at achieving the surrender of a relatively substantial portion of the taxpayers' wealth to enable the government to cope with some nonrecurrent major emergency or to bring about with one stroke a major redistribution of wealth or a major reduction of the note circulation or the national debt. Capital levies were introduced in many European countries after both World War I and World War II.