What was the ancient Roman tax on the value of inherited property called?

The ancient Roman tax on the value of inherited property was called vicesima hereditatium.

The name means “the twentieth of inheritances,” reflecting a rate of one-twentieth, or 5 percent. Emperor Augustus established the tax in AD 6 as the vicesima hereditatium, with proceeds supporting the military treasury known as the aerarium militare.

The tax generally applied to inheritances and legacies, although Roman rules included exemptions and distinctions concerning close family members and the size or status of an estate. Collection was administered through Roman officials and customs-style financial arrangements rather than through a modern inheritance-tax department.

Roman taxation used many different terms, so this levy is easy to confuse with tribute on land, portoria on goods and transport, or the fiscus Judaicus imposed on Jews after the destruction of the Temple. The vicesima hereditatium is one of the clearest ancient precedents for an inheritance tax.