One $3M cash buyer doesn't change the taxable FMV on your house. That price isn't considered in assessments. Now if 10 houses in your neighborhood sold simila

One $3M cash buyer doesn't change the taxable FMV on your house. That price isn't considered in assessments. Now if 10 houses in your neighborhood sold similarily and are roughly equivalent to your house, then your tax would go up. This actually happened in Palo Alto when Zuckerberg bought the houses around his home.