A major argument in support of land-value taxation is that it creates no incentives for altering behavior in order to avoid the tax. By contrast, a conventional property tax, levied on buildings, can deter landowners from erecting otherwise desirable structures on their land. For example, homeowners may decide against finishing a basement or adding a second bath because it would increase tax liability. Thus, a conventional property tax can lead to excessively low capital-land ratios and “excess burden”—a cost to taxpayers over and above the actual monetary payments they make to the tax authorities. This article reports on a recent study of excess burden resulting from an early British antecedent of the modern property tax—the 17th-century window tax.