A supplemental tax bill is generated whenever a property is reassessed due to a change in ownership, or the completion of new construction. The supplemental tax bill (or refund) reflects any increase (or decrease) in property assessment resulting from the supplemental event.

The Kern County Treasurer-Tax Collector has developed an online Supplemental tax bill estimator.

If your Notice of Supplemental Assessment indicates a net increase and the resulting bill exceeds $4.50, a Supplemental Tax Bill will be issued by the Treasurer-Tax Collector. Supplemental Bills are issued 45 days after the Notice of Supplemental Assessment is mailed.

If you want to find out the approximate amount of a supplemental tax bill before you get it, the Kern County Treasurer-Tax Collector has developed an online Supplemental
tax bill estimator.

The sale or transfer of a full or partial interest in property, including a transfer consequent to the death of a property owner, may result in a reassessment and the issuance of a supplemental bill.

Certain forms of property transfer are not subject to reassessment. Exceptions include:

• Interspousal transfer
• Transfer between registered domestic partners
• Addition of joint tenants
• Transfer of property between parents and their children or from grandparents to their grandchildren (Fiscal limits may apply, and an application for exclusion must be filed with the assessor).

For further information, please contact the Assessor's Office Title Department at (661) 868-3300, or view the exclusion forms.

New construction typically involves an improvement to real property, such as a room addition, pool, or garage. An alteration which restores a building to the "substantial equivalent of new" (such as a complete renovation) would also qualify as new construction. Certain types of construction, such as solar panels, are exempt from assessment, and normal repair and maintenance is not considered new construction.

Only the newly constructed portion may be reassessed. The value of the existing property is not affected.

The Assessor determines the fair market value of new construction as of the date of completion or the fair market value of the portion of property transferred as of the transfer date. Once the new value has been determined, the Assessor issues a Notice of Supplemental Assessment indicating the new assessed value and the net change in assessed value.

You have the right to appeal any assessed value if you feel that it exceeds the market value of the property in question, provided that the appeal is filed in a timely manner. Appeal of supplemental assessments must be filed with the Clerk of the Board of Supervisors within sixty (60) days of the mailing date shown on the supplemental bill or the supplemental voucher.

If you feel a supplemental assessment is incorrect, we recommend that you discuss the assessment with the Assessor's Office as soon as possible after receiving notice and prior to filing an appeal. If you can provide the assessor with convincing evidence that the assessment was incorrect, the assessment could be corrected without an assessment appeal hearing.

Important: Filing an appeal does not relieve the applicant from the obligation to pay property taxes on or before the applicable due date shown on the tax bill.

Further information about the appeals process may be obtained by contacting the Clerk of the Board of Supervisors at (661) 868-3585.

The are three reasons why an owner may receive more than one supplemental tax bill:

1. Supplemental event occurred between January 1 and May 31
   • A supplemental tax bill is always generated for the remainder of the fiscal year in which the event occurred.
   • An event occurring between January 1 and May 31 will create a second supplemental assessment for the following fiscal year because the annual assessment roll, established at midnight January 1 for the fiscal year beginning July 1, will not reflect the change in value generated from a January to May event and must be adjusted to account for the change in value.


2. Prior owner had a supplemental event in the same fiscal year
   • You can also receive multiple supplemental bills in situations where a series of supplemental events take place within the same fiscal year for different owners. If the bill for the prior owner's supplemental event is for the same fiscal year in which you took ownership, you will receive a portion of that bill, pro-rated for the time period that you owned the property.


3. Multiple supplemental events occurred while you owned the property
   • If multiple supplemental events (changes in ownership and new construction) occurred while you own the property, you will receive one or two supplemental bills for each of these events. Supplemental assessments are generated for each event.

You may be eligible to receive the Homeowners' Exemption of up to $7,000 of assessed value on a supplemental tax bill if the property you acquired was not already receiving the exemption on the annual tax bill and the property will be your principal place of residence.

New property owners are automatically sent a Homeowners' Exemption claim form, but the exemption is not automatically granted. To receive the full exemption, you must submit a claim to the Assessor's Office no later than the 30th day following the date of notice. An exemption for 80% of the full amount will be granted for a late claim if the claim is filed by the due date of the first tax installment.

The Homeowners' Exemption can only be applied to a supplemental assessment that is a net increase and results in a supplemental tax bill. It cannot be applied to a supplemental assessment lowering the value.