The California Constitution requires that all property be taxed, unless otherwise exempted under the California Constitution or United States Constitution. Article XIII-A of the California Constitution requires that real property only be reappraised when property undergoes a change in ownership or has new construction (see Proposition 13).
Assessment Roll Values
Your tax bill shows land and improvement values. "Improvements" include buildings or anything of a structural nature (such as swimming pools, paving, etc.). When you have an improvement value, it doesn't always mean that you have recently improved your property.
Assessments are made for a fiscal year that runs from July 1st to June 30th the following year. The values on the assessment roll are for the property as of January 1st of the calendar year that the fiscal year starts. This is called the lien date. As an example:
- Fiscal Year 2017-2018 runs from July 1st, 2017 to June 30th, 2018.
- The assessed value on this tax bill is for the ownership and condition of the property as of January 1st, 2017.
Supplemental Assessments pick up changes in assessed value, either increases or decreases, that occur in the middle of a fiscal year. Taxes based on these value changes are prorated from the time of the change to the end of the fiscal year. A Supplemental Assessment can be created due to new construction such as adding a pool or garage, or a change in ownership. The Supplemental bill is in addition to the regular tax bill.