California Porch

California note · Money and taxes

A supplemental property tax bill can arrive after a home purchase

property taxsupplemental billhome purchase

Open a supplemental property tax bill as soon as it arrives. Put each printed delinquency date on your calendar. This bill is separate from the regular annual bill. The Board of Equalization says it goes to the property owner, not the mortgage lender. Do not assume an impound account or closing payment covered it.

A change in ownership or finished new construction can lead to this bill. The assessor compares the old and new taxable values for the rest of the fiscal year. A net increase creates a supplemental bill. A net decrease can lead to a refund.

A change from January 1 through May 31 generally creates two supplemental assessments. That is because it affects two fiscal years. A change from June 1 through December 31 generally creates one. You must still pay the regular annual bill on its own schedule.

Ask the county assessor about the value or effective date. Ask the county tax collector about the bill, installment dates, payment record, or a copy. Keep the deed, closing statement, annual bill, and supplemental notice together. If an expected bill never comes, contact the tax collector.

Where to see it

California Board of Equalization supplemental assessment and change-in-ownership pages, plus the county assessor and tax collector.

Official sources

Official source trail

Reviewed July 14, 2026

California Porch explains the path. The official source is still the place to confirm the current rule, fee, form, map, deadline, or office decision.

Use the official page before you spend money, file paperwork, rely on a deadline, or change a property.

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