Let's say you bought a home several years ago for $100,000. The Assessor determined that the purchase price was the fair market value, so the new base year value of the property was set at $100,000.
California Revenue and Taxation Code Section 51(a)(2)
A Proposition 8 reduction is a form of assessment relief. It may be applied by the Assessor when a property's assessed value exceeds the current market value. By the end of June all Santa Clara County property owners receive notification of their assessed value.