Supplemental Property Taxes

Your Supplemental Property Tax Bill will contain information about the new value at the date of purchase or at completion of new construction. The Assessed Value for the current fiscal year will be subtracted from this, yielding the net supplemental value. Additionally, the Supplemental Property Tax Bill may be prorated if you did not own the property for the entirety of the fiscal year.

Reference

Property Tax Reports and Documents

Frequently Asked Questions

What is meant by new construction or change of ownership?

New construction includes any addition to real property or any substantial alteration to an existing structure which requires a building permit.

A change in ownership occurs when title to the property is transferred. Transfer can be caused by sale, inheritance, or seizure.

Exclusions may be granted, but require the filing of documentation with the Assessor’s Office. For claim forms or further information regarding the requirements for filing exclusions contact the Assessor at (805) 781-5643.

Am I entitled to an Exemption on my Supplemental Tax Bill?

You may be eligible for an Exemption on your Supplemental Tax Bill, which would result in a reduction of taxes. Applications for homeowner, veteran, church, welfare, or other exemptions may be obtained at Property Exemption Information or from the Assessor's Office at (805) 781-5643.

What happens when the Assessor reassesses my property?

The Assessor determines a new value for the property. The Assessor then calculates the difference between the new value (set at the time of purchase or completion of new construction) and the previous value. This results in the Supplemental Assessment Value. Once the new assessed value of your property has been determined, the Assessor will send you a Notice of Supplemental Assessment.

Example:

New value at date of purchase or completion of new construction $220,000
Assessed Value for current fiscal year -200,000
Supplemental Assessment Value $ 20,000


Supplemental Taxes are calculated based on the difference (or increase) in values. As a result, one or more Supplemental Tax Bills will be issued. 
If the reassessment results in a reduction in value, a refund will be issued by the Auditor-Controller'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 before a refund can be issued.

Do I have the same right to appeal the Assessor's Supplemental Assessed Value as I do the Annual Assessed Value?

Yes, however, you should first discuss the matter with the Assessor's Office to schedule an informal assessment review. If the matter is not resolved to your satisfaction, there is an Assessment Appeals Board established to formally appeal the assessment. Appeals must be filed within sixty (60) days of the mailing date shown on the Notice of Supplemental Assessment sent by the County Assessor’s Office.

If you are appealing your assessment, your Supplemental Tax Bill(s) should be paid before they become delinquent. If left unpaid, penalties may accrue during the appeal process. If the outcome of your appeal results in a refund, it will be issued by the Auditor-Controller's Office.

Further information regarding the appeals process can be obtained by calling (805) 781-5080, or writing to: County Clerk, Room D-120, County Government Center, San Luis Obispo, California, 93408. Assessment Appeals

Types of Supplemental Tax Bills

There are two types of Supplemental Tax Bills, secured and unsecured.

Secured Supplemental Tax Bills are issued to the current real property owner and are attached by a lien to the property. If you are not the current real property owner, and you have received a Secured Supplemental Tax Bill please contact the Tax Collector’s Office at (805) 781-5831 or by email at ttc@co.slo.ca.us

Unsecured Supplemental Tax Bills are issued to prior owners, or on unsecured property such as mobilehomes and possessory interest assessments. There is no real property to attach the lien to, and the bill is issued to the individual. If you currently own the real property referenced on the bill and you have received an Unsecured Supplemental Tax Bill please contact the Tax Collector’s Office at (805) 781-5831 or by email at ttc@co.slo.ca.us

If I receive a Supplemental Tax Bill, will I also receive an annual tax bill in November?

Yes, the Supplemental tax Bill is in addition to the annual tax bill. Both bills must be paid by their respective delinquent dates. For information on the annual tax bill, see the section, Secured Property Taxes.

If I pay my property taxes through an impound account, will my Supplemental Tax Bill be sent to my lender?

No, Supplemental Tax Bills are mailed directly to you. It is your responsibility to contact your lender to determine who will pay the Supplemental Tax Bill.

Can delinquent penalties be waived if my lender fails to make my payment?

No, the California Revenue and Taxation Code does not authorize the County Tax Collector to remove penalties in this situation.

Will I receive a Supplemental Tax Bill if I purchase property and then sell it again after a few months?

If the reassessment results in an increase you will receive a Supplemental Tax Bill for the period that you owned the property. The new owner of the property will receive a separate Supplemental Tax Bill from their date of purchase. You may not receive the Supplemental Tax Bill until after you transfer the property to the new owner.

Check the dates used in prorating your Supplemental Tax Bill to ensure that the period covered is correct. If you believe the proration period is incorrect, contact the Assessor's Office at (805) 781-5643.

When I purchase property or complete construction 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 remaining portion of the year, from the date you purchased the property or completed new construction. However, if the purchase date or the construction completion date was after January 1, you will receive an additional Supplemental Tax Bill for the following fiscal year.

What information is shown on the Supplemental Tax Bill?
  • The fiscal year for which the taxes are assessed.
  • The legal description of the property.
  • The old and the new Assessed Values and the difference (net Supplemental Value) upon which the tax is computed.
  • The type and amount of any Exemptions, if applicable.
  • The total amount of taxes due.
  • The due and delinquent dates.
When do Supplemental Tax Bills have to be paid?

The date on which Supplemental Tax Bill(s) become delinquent varies, depending upon when they are mailed by the County Tax Collector.

For Bills Mailed in: 1st Installment Delinquent Date 2nd Installment Delinquent Date
July December 10 April 10
August December 10 April 10
September December 10 April 10
October December 10 April 10
November December 31 April 30
December January 31 May 31
January February 28 June 30
February March 31 July 31
March April 30 August 31
April May 31 September 30
May June 30 October 31
June July 31 November 30


Penalties of 10% are added to any installment which is not paid before the delinquency date, and an additional delinquent cost is added to a late 2nd installment.

What happens if I fail to pay my Secured Supplemental Tax Bill?

If your Supplemental Tax Bill is not paid by the end of the fiscal year the property becomes tax-defaulted. If the taxes remain unpaid for a maximum of five years following tax-default, your property becomes subject to the County Tax Collector's Power to Sell.  See Payment of Delinquent Property Taxes.

What happens if I fail to pay my Unsecured Supplemental Tax Bill?

If your Supplemental Tax Bill was Unsecured at billing, different laws apply. If your bill is not paid by June 30, and is given a prior year tax status a lien may be recorded which will affect your credit. Additional fees, interest and a Release of Lien Fee will be charged, in addition to the original tax amount. Delinquent collection cost(s) may also be added as collection efforts are taken.