Short answers, pulled from the story.
Property tax is an ad valorem tax levied on the value of a property, most commonly expressed as a percentage or as a mill rate, where one mill equals one-thousandth of a currency unit. To calculate the bill, the governing authority multiplies the assessed value of the property by the mill rate and divides by one thousand. The assessed value itself can be based on market value, cadastral rental value, or other measures depending on the jurisdiction.
The earliest known tax records date from about six thousand years BCE, in the form of soil tablets found in the city-state of Lagash, now in the territory of Iraq. Ancient Egypt also levied taxes on the value of grain, cattle, oil, beer, and land, assessed by literate tax assessors who kept records of land ownership and size.
A mill rate, also called millage, expresses the property tax as the amount of tax per one thousand currency units of a property's assessed value. One mill equals one-thousandth of a currency unit. A municipality with a mill rate of 20 mills, for example, calculates the annual tax by multiplying the assessed property value by 20 and dividing by 1,000.
China does not tax homeowners because the government owns all land. Several territories in the United States, including American Samoa, the Territory of Palmyra Island, and Kingman Reef, have no tax on private land. In Alaska, only 24 municipalities levy a property tax, leaving the vast majority of the land mass untaxed.
In 2018, the German Federal Constitutional Court ruled that the property tax assessment system violated Article 3 of the Basic Law, which guarantees equality before the law. Standard values used in the former West Germany had not been updated since 1964, and those in the former East Germany dated from 1935. A reform required all property owners to submit reassessments as of the 1st of January 2022, with new taxes based on those values levied from the 1st of January 2025.
France introduced a tax on vacant properties in 1999, which reduced the vacancy rate by 13 percent. The taxe annuelle sur les logements vacants applies to unfurnished, unoccupied dwellings in government-designated tight housing markets that have been left empty for at least one year. A separate tax, payable to municipalities that opt into it, applies to homes unoccupied for more than two years.