If you've received a notice from our office, read it carefully — the steps you may need to take and any deadlines depend on the type of notice you received.

What Is a Supplemental Assessment?

When you buy a property or complete new construction, this triggers what's called a supplemental event. The Assessor's Office is required by law to reassess the property's value as of the date that event occurred.

This reassessment results in a supplemental assessment, which captures the difference between the property's previous assessed value and its new assessed value. Because this happens mid-year, the amount is prorated based on how many months remain in the fiscal year (July 1 – June 30).

Important: A Notice Is Not a Tax Bill

The notice you received from the Assessor's Office is not a bill. It tells you the new assessed value we have determined for your property.

A separate tax bill will be created and mailed by the Tax Collector’ Office approximately 30–60 days after the date on your notice. The Assessor's Office does not issue tax bills and cannot tell you exactly when your bill will arrive or what the final amount will be.  However, as a general estimate, property taxes are approximately 1.2% of the assessed value.

How to Read Your Notice

Your notice contains several key pieces of information:

  • Owner name and mailing address — verify these are correct
  • Date of notice — this starts the clock on your 60-day window to file an assessment appeal if you disagree with the value
  • Assessor's Parcel Number (APN) and property address — identifying information for your property
  • Date of the supplemental event — the date of your change in ownership or completion of new construction
  • Assessed values — shown at the bottom of the notice

How the Assessment Is Calculated

  1. A supplemental event occurs — such as purchasing a home or completing an addition
  2. We determine fair market value — based on the property's value as of the event date (not necessarily the purchase price)
  3. We calculate the difference — the new assessed value minus the prior assessed value equals the net supplemental value
  4. We mail the supplemental notice  - A supplemental notice is mailed to the primary owner of record
  5. The value is prorated — adjusted for the number of months remaining in the fiscal year
  6. A tax bill is generated — by the Tax Collector’s Office based on the enrolled value

How Many Bills Will I Receive?

  • Event date January 1 – May 31: You will receive two supplemental tax bills. The second bill covers the full upcoming fiscal year beginning July 1.
  • Event date June 1 – December 31: You will receive one supplemental tax bill, covering the period from the month after your event date through June 30.

What Should I Do Next?

If everything looks correct: No action is needed. Your tax bill will arrive from the Tax Collector’s Office within 40–60 days.

If you have questions: Contact the Assessor's Office by phone, email, or in person to request an informal review. We can explain what triggered the notice and how the value was determined.

If you disagree with the assessed value: You have 60 days from the date of the notice to:

  • File a Base Year Value Review with the Assessor's Office, and/or
  • File an Assessment Appeal Application with the Clerk of the Board's Office
For more information, see Contesting Your Assessed Value.

What Is an Escape Assessment?

An escape assessment is a correction to a property's assessed value for one or more prior years. It occurs when a taxable event — such as new construction or a change in ownership — was not discovered and assessed at the time it occurred.

Example: You added a room to your home in September 2022, but our office did not discover the addition until September 2024. An escape assessment would be issued to capture the value of that room for each tax year it was missed.

Common Reasons for an Escape Assessment

  • Unreported or overlooked new construction — such as work done without a building permit
  • Change in ownership not reported timely — for example, when a property owner passes away and the executor of the estate does not notify our office
  • Change in control or ownership of a legal entity that owns real property
  • Removal of an exemption that was previously applied to the property
  • Business property — a property statement filed late, not filed at all, or property discovered during an audit

Important: A Notice Is Not a Tax Bill

The Notice of Escape Assessment you received from the Assessor's Office is not a bill. It informs you of the proposed assessed value for each prior tax year affected.

A separate escape tax bill will be created and mailed by the Tax Collector’s Office after the assessment is enrolled. The Assessor's Office does not issue tax bills and cannot tell you exactly when your bill will arrive or what the final amount will be.  However, as a general estimate, property taxes are approximately 1.2% of the assessed value per year.

How to Read Your Notice

Your notice contains several key pieces of information:

  • Owner name and mailing address — verify these are correct
  • Date of notice — this starts the clock on your 60-day window to file an assessment appeal if you disagree with the value
  • Assessor's Parcel Number (APN) and property address — identifying information for your property
  • Date of the escaped event — when the change in ownership or new construction originally occurred
  • Assessed values by tax year — shown at the bottom of the notice, with a proposed escape assessment amount for each year affected

How the Assessment Is Calculated

  1. An escaped event is discovered — such as unreported construction or an ownership change that was not recorded
  2. We determine fair market value — based on the property's value as of the date the event originally occurred
  3. We calculate the escape assessment — the new assessed value minus the prior assessed value for each affected year
  4. We send you the notice – Escapes will generate two different notices.  The first notice is the “Notice of Proposed Escape Assessment” and 10 days later the 2nd notice, “Notice of Enrollment of Escape Assessment” is mailed.
  5. The assessment is enrolled — for each tax year that was missed, going back up to the applicable statute of limitations
  6. A tax bill is generated — by the Tax Collector’s Office based on the enrolled values

What Should I Do Next?

If everything looks correct: No action is needed. Your escape tax bill will arrive from the Auditor-Controller's Office after the assessment is processed.

If you have questions: Contact the Assessor's Office by phone, email, or in person to request an informal review. We can explain what triggered the notice and how the values were determined.

If you disagree with the assessed value: You have 60 days from the date of the notice to:

  • File a Base Year Value Review with the Assessor's Office, and/or
  • File an Assessment Appeal Application with the Clerk of the Board's Office

For more information, see Contesting Your Assessed Value.

What Is an Annual Assessment Notice?

Each year, the Assessor's Office reviews property values across Santa Cruz County. An Annual Assessment Notice is generated when required by statute or when a property's assessed value increases by more than the annual Proposition 13 inflation adjustment (typically 2%). You will only receive a notice when one of these conditions applies.

Starting in 2026, all annual notices are posted online with confidential information redacted. To view your notice, visit the Parcel Lookup, enter your parcel number, and navigate to Assessed Values. If no notice was generated for your property, the lookup will indicate that no notice exists.

Common Reasons Your Assessed Value May Have Changed

  • Construction in progress — if you have an active building permit, the value of the unfinished construction may be added to your assessment each year until the project is complete
  • Decline in value — if your property is in a decline in value status, the assessor’s office reviews and adjusts the value each year, based on current market conditions, until the factored base year value (Prop 13) value is restored.  Properties on DIV will receive an annual notice advising of the office opinion of market value for that year.
  • Depreciation of personal property — for business owners, the assessed value of equipment and other personal property is adjusted annually to reflect depreciation

Important: A Notice Is Not a Tax Bill

The Annual Assessment Notice you received from the Assessor's Office is not a bill. It informs you of the updated assessed value that will be used to calculate your property taxes.

Your annual property tax bill will be mailed separately by the Tax Collector’s Office in October. The Assessor's Office does not issue tax bills and cannot tell you the exact amount you will owe.

As a general estimate, property taxes are approximately 1.2% of the assessed value.

What Should I Do Next?

If everything looks correct: No action is needed. Your annual property tax bill will be mailed by the Tax Collector’s Office in the fall.

If you disagree with your assessed value, you have several options:

  • Request an explanation — contact our office for an informal review before taking any formal action
  • File a Decline in Value Review application — must be filed with the Assessor's Office by December 31st
  • File an Assessment Appeal application — must be filed with the Clerk of the Board's Office by November 30th

For applications and more information, visit our Declines in Value page.