A property tax (whose rate is expressed as a percentage or per mille, also called millage) is an ad valorem tax on the value of a property.

The tax is levied by the governing authority of the jurisdiction in which the property is located. This can be a national government, a federated state, a county or geographical region or a municipality. Multiple jurisdictions may tax the same property.

Often a property tax is levied on real estate. It may be imposed annually or at the time of a real estate transaction, such as in real estate transfer tax. This tax can be contrasted to a rent tax, which is based on rental income or imputed rent, and a land value tax, which is a levy on the value of land, excluding the value of buildings and other improvements.

Under a property-tax system, the government requires or performs an appraisal of the monetary value of each property, and tax is assessed in proportion to that value.