Supplemental Tax Estimator - Real Property

The tax estimator is designed to help new and prospective homeowners reduce confusion concerning the amount of property taxes they can expect to pay following their purchase.

(Please enter property address.)

(Please enter the APN number with or without dashes: 12345678 or 123-45-678)

Please Read:

  • Admittedly complicated and confusing, Supplemental Assessments were created by Senate Bill 813 in 1983 to close what was perceived as loopholes and inequities in Proposition 13.
  • Prior to the creation of supplemental assessments, changes in assessed value due to a change in ownership or completion of new construction would not result in higher taxes until the tax year (July 1 to June 30)following the lien date when the new values were placed on the assessment roll. In some instances, taxes on the new assessments would not be collected for up to 21 months. This resulted in serious differences in tax treatment for transactions that may have only been separated by one day. Supplemental assessments are designed to identify changes in assessed value (either increases or decreases,) that occur during the fiscal year such as changes in ownership and new construction. They are in addition (supplemental) to the traditional annual assessment and property tax bill. A tax bill is issued only on the added value, and is prorated for the remaining portion of the fiscal year. For the next fiscal year, the entire new assessed value of the real property is added to the regular assessment roll. The increase in value is taxed from the first of the month following the date of completion of new construction or the change in ownership.
  • To learn more go to FAQ - General Questions.
  • The following information from the Tax Collectors Office may also be helpful.