Supplemental Assessments and Notices

Depending on the date of change of ownership or completion of new construction, you may receive one or two supplemental bills:

If a change of ownership or completion of new construction event occurs on or after June 1 but before January 1, there will be One (1) Supplemental Assessment because it impacts one fiscal year.
  • A single supplemental assessment based on the difference between the new base year value (market value) and the assessed value on the current Secured Roll (the previous owner's Prop. 13 value)

Generally, a supplemental assessment is prorated based on the number of months remaining in the fiscal year. Thus, for a December transfer, which increases the assessment value by $50,000, the supplemental assessment would be the $50,000 additional value prorated for six months (January 1 - June 30).

If a change of ownership or completion of new construction occurs between lien date (January 1) and May 31, there are two supplemental assessments because it impacts two fiscal years.

  • The first supplemental assessment is based on the difference between the new base year value (market value) and the assessed value on the current Secured Roll
    (Prop. 13 value). This is for the remaining portion of the current fiscal year ending June 30.
  • The second supplemental assessment is based on the difference between the new base year value (market value) and the assessed value to be enrolled on the Secured Roll being prepared. This will be for the new fiscal year beginning July 1.

View Informational Insert Mailed With Supplemental Notices

Supplemental Assessment Effective Date

When calculating supplemental assessments, the effective date is carried over to the first day of the month following the date of the transfer (a purchase or change in ownership) or completion of new construction. For example, if a deed is recorded or if new construction is completed on May 15th, the date on the supplemental assessment will be June 1.

Homeowners' Exemption on a Supplemental

If the property purchased after lien date (January 1) has a homeowners' exemption, it will remain in effect for the remainder of the upcoming fiscal year. If the property did not have a homeowners' exemption when it was purchased, the homeowner has thirty (30) days from the mailing of the Notice of Supplemental Assessment to file a claim. To receive additional information, please call (714) 834-3821.

The Homeowner's Exemption Form is not available on-line.

Builders' Exclusion

Under Section 75.12 of the Revenue and Taxation Code, developers' and owner-builders' newly-constructed real property will not trigger a supplemental assessment provided the property is constructed for the purpose of marketing the property, and the owner/builder notifies the Assessor, in writing, prior to or within thirty (30) days of the commencement of construction. If a property is built for resale and is subdivided into five or more parcels, the exclusion is automatic and the owner is not required to notify the Assessor.

Once the property changes ownership, is rented, leased, or otherwise used by the developer or owner-builder, a supplemental assessment is made. The date of completion of new construction is "conclusively presumed" to be the date the new construction is available for use by the developer or owner-builder. To request an application form or additional information, please call (714) 834-5674.

Supplemental Assessment Appeals

A taxpayer has sixty (60) days from the date of the mailing of the Notice of Supplemental Assessment within which to file an assessment appeal for that valuation.

Contact the Clerk of the Board of Supervisors for an Application for Changed Assessment, or for further assistance please call (714) 834-2331.

Supplemental Tax Bills - Taxes Due

Supplemental tax bills are due on the date mailed and are payable in two installments.

Bills mailed from July to October are delinquent on the same dates as the annual secured property tax bills (December 10 and April 10).

For bills mailed from November to June, the first installment is delinquent on the last day of the month following the month in which the bill is mailed, and the second installment is delinquent on the last day of the fourth month following the date the first installment is delinquent.

If you have any questions about your supplemental tax bills, please contact the Tax Collector at (714) 834-3411.