Currently, Prop 13 caps property taxes as a percent of the last sale price. What if instead we allowed property taxes to increase with home value, but deferred collection of the incremental tax increase until the sale of the home? The back taxes owed could even be capped as a percent of appreciation. Given that the property's price has by definition increased, even after paying the back taxes the seller still gets much of their money back, the government comes out whole, we don't force old people to sell prematurely and the tax burden is shared more equitably between old and new owners.