Under state law, property is reappraised upon completion of new construction or change of ownership. A supplemental tax bill is an additional property tax bill based on the difference between the prior assessed value and the new assessed value of real property. A supplemental tax bill is in addition to the regular tax bill, which is based on the assessed value as of January 1st. The supplemental tax bill is sent directly to you by the Treasurer / Tax Collector rather than to your mortgage company as may be the case with the regular property tax bill.

The State of California passed the supplemental assessment law in 1983 to provide additional funding primarily for schools. It merely accelerates the effective date of reappraisals made according to Proposition 13 laws.

The supplemental tax bill covers the period of time from the change of ownership date or completion of new construction date, to the end of the fiscal year (June 30th) If the change-of-ownership or new construction occurs between January 1st and May 31st, a second supplemental assessment will be required for the next fiscal year (July 1 through June 30). If two assessments are required, two separate bills will be issued.

The supplemental bill is normally issued within six months after the close of escrow, or completion of new construction. If the new value of the property is less than the previous assessed value, there will be a refund issued to the owner. If another sale or transfer of the property occurs before the mailing of the supplemental tax bill, the supplemental taxes will be prorated between the owners.

If you disagree with the value, you must file an assessment appeals application with the Clerk of the Board within 60 days of the mailing date of the supplemental value notice.

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