What is Supplemental Tax Bill?
A supplemental tax bill is a one-time California property tax adjustment issued after you buy a home, covering the difference between the seller’s old assessed value and your new, higher purchase-price assessment for the rest of the tax year. It arrives separately from your regular tax bill and often isn’t covered by your initial impound account. New buyers should budget for it.
Example: A few months after closing, a buyer receives a supplemental tax bill reflecting the jump from the prior owner’s assessed value to their purchase price.