In France, it is the most important source of state finance, accounting for approximately 45% of state revenues. A property tax, millage tax is an "ad valorem" tax that an owner of real estate or other property pays on the value of the property being taxed. There are three species or types of property: Land, Improvements to Land (immovable man made things), and Personal (movable man made things). Real estate, real property or realty are all terms for the combination of land and improvements. The taxing authority requires and/or performs an appraisal of the monetary value of the property, and tax is assessed in proportion to that value. Forms of property tax used vary between countries and jurisdictions. "Ad valorem" duties are important to those importing goods into the United States because the amount of duty owed is often based on the value of the imported commodity. "Ad valorem" taxes (mainly real property tax and sales taxes) are a major source of revenues for state and municipal governments, especially in jurisdictions that do not employ a personal income tax. Virtually all state and local sales taxes in the United States are "ad valorem". ""Ad valorem"" is used most frequently to refer to the value placed on property by the county tax assessors. An assessment is made against this value by applying an assessment rate (e.g. 100%, 60%, 40%, etc.). The net assessment is determined after subtracting any exemptions to which the property owner is entitled (e.g. homestead exemptions), and a tax or millage rate is applied to this net assessment to determine the ad valorem tax due from the property owner. The two main basis for determining the ad valorem value are fair market value and current use value. The fair market value is based on the typical selling price for property on which the buyer and seller can agree, with the assumption that the property is being used or will be used at its highest and best use after the sale. The current use value is the typical selling price for property with an assumption that it will continue after the sale to be used in its current use rather than being converted to its highest and best use. State legislatures have created many variations to these two main valuation approaches. In some states, a central appraisal authority establishes values on all properties and distributes these to the local county or jurisdiction taxing authority, which then sets a tax rate and imposes the local ad valorem tax. In other states, a central appraisal authority values certain properties that are difficult to value at the local level (e.g. railroads, electric companies and other utility companies) and sends these values to the local county or jurisdiction taxing authority, while the local tax assessors determine the value on all other property in the county or jurisdiction.