Tax systems typically include multiple types of taxes that share related tax bases. Consequently, taxpayers’ responses to one tax can affect the revenue generated by other taxes. Our research examines how the United to House Los Angeles measure (Measure ULA), also known as the mansion tax, affects the city’s property tax base. Effective April 2023, Measure ULA imposed a 4 percent tax on property transactions between $5 million and $10 million and a 5.5 percent tax on transactions exceeding $10 million, in addition to the standard 0.56 percent tax on all property transactions. However, these thresholds have since increased in line with inflation.