Supplemental Property Taxes FAQs

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Oscar J. Garcia, CPA, Auditor-Controller/Treasurer-Tax Collector

What are "supplemental" property taxes?

"Supplemental" taxes are additional secured taxes that are due when property undergoes a change in ownership or new construction. The additional tax is owed because the County Assessor is required to immediately adjust the January 1 value to reflect the new value of the property. Adjusted for the number of months left in the fiscal year, the supplemental tax bill represents the tax due on the difference between the old and new values.

What is meant by new construction or change of ownership?

Typically, new construction is any substantial addition to real property, such as original construction, adding a new room, pool, or garage; or any substantial alteration, which restores a building, room, or other improvements to the equivalent of new.

Most changes in ownership caused by the sale of property results in reassessment. However, inter-spousal transfers, the transfer, sale, or inheritance of property between parents and their children and the addition of joint tenants do not result in the reappraisal of property values. Parent/child transfers require exemption filings within a limited period.

Information or claim forms regarding assessment issues should be referred to the Assessor’s Office, (559) 600-3534

What happens when the assessor reassesses my property?

The Assessor first determines the new value of the property based on current market values. The Assessor then calculates the difference between the new value, set at the time of purchase or completion of new construction, and the old value (set on the January 1 lien date). This results in the supplemental assessment value. Once the new assessed value of your property has been determined; the Assessor will send you a notification of the amount.


New value at date of purchase or Completion of new construction $120,000
Assessed value for current fiscal year $100,000
Supplemental assessment value will be $20,000

This reassessment usually results in an increase in property value, in which case your supplemental taxes will be calculated based on the change in value and one or more supplemental tax bills will be created and mailed to you by the Tax Collection Unit of the Auditor-Controller/Treasurer-Tax Collector’s office. In some instances the reassessment results in a reduction in value, in which case a refund will be mail by the Special Accounting Division of the Auditor-Controller’s Treasurer-Tax Collector’s office. A reduction in value will not reduce the amount due on the annual tax bill. The annual tax bill must be paid in the amount originally billed.

Do I have the same right to appeal the assessor’s supplemental assessed value as I do the annual assessed value?

Yes. You may take the matter up with the Assessor to see if that office will change the valuation. The Board of Supervisors has established an Assessment Appeals Board for the purpose of resolving valuation problems. Application for appeal must be filed within sixty days of the date of notice.

If you choose to appeal your assessment, you should still pay your tax installments in full by the appropriate deadlines; otherwise, you may incur penalties while the case is in appeals. If your appeal is granted, the Special Accounting Division of the Auditor- Controller/Treasurer-Tax Collector’s office will process a refund.

If I receive a supplemental tax bill, will I also receive a tax bill in November each year?

YES. The supplemental tax bill is in addition to the annual tax bill and both must be paid as specified on the bill.

If I pay my property taxes through an impound account will my supplemental tax bill be sent to my lender?

No. Unlike the annual tax bill, lending agencies do not receive a copy of the supplemental tax bill. When you received a supplemental tax bill, you must contact your lender to determine who will pay the bill, you or your lender.

What if I purchase a piece of property and then sell it again after a few months?

If you purchase and then sell property within a short period of time, the supplemental tax bill you received should cover only those months during which you owned the property and the new owner should receive a separate supplemental tax bill. Because of the number of properties changing hands each year, there may be delays in placing new assessments on the tax roll. Be sure to check the date used to prorate the bill to ensure that the period covered is the period during which you actually owned the property.

When I purchase property or complete construction at some point during the fiscal year, will I be taxed on the supplemental value for the entire fiscal year?

NO. You are only taxed on the supplemental value for the portion of the current fiscal year remaining after you purchased the property or completed new construction, however, if the event was prior to January 1, you will receive an additional supplemental tax bill for the next fiscal year.

When are supplemental tax payments made?

The date on which supplemental tax bills become delinquent varies depending upon when they are mailed. If the bill is mailed between July 1 and October 30, the taxes become delinquent at 5 p.m. on December 10 for the first installment and 5 p.m. on April 10 for the second installment. This is the same delinquency schedule as the annual secured tax bills.

If the bill is mailed between November 1 and June 30, the delinquency dates, which are shown on the tax bill, are determined as follows: the first installment is delinquent at 5 p.m. on the last day of the month following the month the bill was mailed; the second installment is delinquent at 5 p.m. on the last day of the fourth month after the first installment delinquency date.

Penalties of 10% are added to any installment which is not paid timely and an additional $10.00 charge is added to a late second installment payment.

If payment of the supplemental tax bill is not made before the delinquency date because of misunderstanding between my lender and myself, may I have the penalties excused?

No, there is no provision in State law to waive penalties under this circumstance.

What happens if I fail to pay my supplemental tax bill?

The same laws apply as for unpaid annual tax bills. If your supplemental tax bill is not paid by June 30 after which the second installment became delinquent, the property becomes tax-defaulted. This is the case even if you have paid your annual tax bill. At the end of the fifth year of delinquency, the property becomes subject to the Tax Collector’s power of sale.

Am I entitled to a homeowners exemption on my supplemental tax bill?

You may very well be eligible for a homeowner’s exemption on your supplemental tax bill. Exemptions, however, are not granted automatically; you must apply to the Assessor before the 30th day following the Assessor’s date of the notice of your supplemental assessment. As long as the home you purchased did not reflect the homeowner’s exemption on the current year’s assessment, and as long as you occupy the home as your principal residence within 90 days of the purchase date, you will be allowed the full $7,000 amount on your supplemental assessment. If your newly acquired home did reflect the full homeowner’s exemption on the secured tax roll, you are not eligible to receive the exemption on your supplemental assessment.

Are other exemptions and assistance programs available that will help defray the amount of supplemental taxes due?

Yes, Supplemental taxes are eligible for the same property tax exemptions and assistance programs as your annual taxes. In addition to the homeowner’s exemption, you may apply for other assessment exemptions such as veterans, church, and welfare. You must file for all exemptions before the 30th day following the date of the Assessor’s supplemental assessment notice. For further information contact the Assessor’s Office at (559) 600-3534.

At this time the State of California is not offering tax assistance or postponements. For information regarding the Homeowner’s Assistance Programs visit and search for HRA. For information regarding the Property Tax Postponement Program visit