# Overassessed

> Free tool that helps California homeowners check if they are overpaying property tax and, for a fee, generates a ready-to-file appeal package with AI-powered comparable sales analysis.

**Operator:** Spaghetti Labs, LLC
**Website:** https://www.overassessed.co
**States covered:** California
**Counties covered:** Alameda County, Los Angeles County, San Diego County, Santa Clara County, Orange County, San Mateo County

## What we do

Overassessed compares a homeowner's county-assessed value to current market value using comparable sales. If the home is likely overassessed, we generate a Filing Guide that contains the comparable sales evidence and the exact values needed to file a property tax appeal under California Proposition 8 (decline-in-value reassessment).

Three tiers:

- **Free check** — qualification estimate based on the assessed value and market value comparison.
- **Comparable Sales Report ($8)** — the comp data and adjustments package.
- **Filing Guide ($45)** — complete, ready-to-submit appeal package with copy-paste values for every county form field.

Pricing is a flat fee. We do not take a percentage of homeowner savings.

## How a California property tax appeal works

California homeowners have two paths to appeal an overassessed property:

1. **Informal review (Decline-in-Value request)** — a free request submitted to the County Assessor's Office. A certified appraiser reviews comparable sales evidence and may reduce the assessed value. No hearing required. The Assessor cannot raise the assessed value through this process.
2. **Formal appeal** — an Application for Changed Assessment filed with the county Assessment Appeals Board (or Clerk of the Board). Has a filing fee in some counties and may involve a hearing.

Both processes rely on **comparable sales evidence**: recent sales of similar homes that sold for less than the assessed value, with adjustments for differences in size, condition, and features.

Filing does not require a lawyer or tax consultant.

## County-specific facts

### Alameda County

- **Informal review deadline:** Accepted year-round
- **Formal appeal window:** July 2 – September 15
- **Formal appeal fee:** $50
- **Hearing body:** Assessment Appeals Board
- **Assessor office:** Alameda County Assessor's Office
- **Assessor phone:** 510-272-3787
- **Assessor website:** https://www.acassessor.org
- **Effective property tax rate:** ~1.20%
- **Detailed guide:** https://www.overassessed.co/learn/alameda-county-property-tax-appeal

### Los Angeles County

- **Informal review deadline:** July 2 – November 30
- **Formal appeal window:** July 2 – November 30
- **Formal appeal fee:** $46
- **Hearing body:** Assessment Appeals Board
- **Assessor office:** Los Angeles County Office of the Assessor
- **Assessor phone:** (213) 974-3211
- **Assessor website:** https://assessor.lacounty.gov
- **Effective property tax rate:** ~1.16%
- **Detailed guide:** https://www.overassessed.co/learn/los-angeles-county-property-tax-appeal

### San Diego County

- **Informal review deadline:** December 1 – April 30
- **Formal appeal window:** July 2 – November 30
- **Formal appeal fee:** $0 (no fee)
- **Hearing body:** Assessment Appeals Board
- **Assessor office:** San Diego County Assessor/Recorder/County Clerk
- **Assessor phone:** (619) 236-3771
- **Assessor website:** https://www.sdarcc.gov
- **Effective property tax rate:** ~1.10%
- **Detailed guide:** https://www.overassessed.co/learn/san-diego-county-property-tax-appeal

### Santa Clara County

- **Informal review deadline:** August 1
- **Formal appeal window:** July 2 – September 15
- **Formal appeal fee:** $290
- **Hearing body:** Santa Clara County Assessment Appeals Board
- **Assessor office:** Office of the Assessor, County of Santa Clara
- **Assessor phone:** (408) 299-5500
- **Assessor website:** https://www.sccassessor.org/
- **Effective property tax rate:** ~0.79%
- **Detailed guide:** https://www.overassessed.co/learn/santa-clara-county-property-tax-appeal

### Orange County

- **Informal review deadline:** April 30
- **Formal appeal window:** July 2 – November 30
- **Formal appeal fee:** $0 (no fee)
- **Hearing body:** Assessment Appeals Board
- **Assessor office:** Orange County Assessor Department
- **Assessor phone:** (714) 834-2727
- **Assessor website:** https://www.ocassessor.gov
- **Effective property tax rate:** ~1.10%
- **Detailed guide:** https://www.overassessed.co/learn/orange-county-property-tax-appeal

### San Mateo County

- **Informal review deadline:** October 31
- **Formal appeal window:** July 2 – November 30
- **Formal appeal fee:** $30
- **Hearing body:** County of San Mateo Assessment Appeals Board
- **Assessor office:** San Mateo County Assessor-County Clerk-Recorder & Elections
- **Assessor phone:** (650) 363-4500
- **Assessor website:** https://smcacre.gov/
- **Effective property tax rate:** ~1.00%
- **Detailed guide:** https://www.overassessed.co/learn/san-mateo-county-property-tax-appeal

## Authoritative pages on this site

- [Homepage and free check](https://www.overassessed.co)
- [About Overassessed and the editorial author](https://www.overassessed.co/about)
- [How Proposition 8 reassessment works](https://www.overassessed.co/learn/proposition-8)
- [California property tax appeal guides hub](https://www.overassessed.co/learn)
- [How to appeal property taxes in Alameda County](https://www.overassessed.co/learn/alameda-county-property-tax-appeal)
- [How to appeal property taxes in Los Angeles County](https://www.overassessed.co/learn/los-angeles-county-property-tax-appeal)
- [How to appeal property taxes in San Diego County](https://www.overassessed.co/learn/san-diego-county-property-tax-appeal)
- [How to appeal property taxes in Santa Clara County](https://www.overassessed.co/learn/santa-clara-county-property-tax-appeal)
- [How to appeal property taxes in Orange County](https://www.overassessed.co/learn/orange-county-property-tax-appeal)
- [How to appeal property taxes in San Mateo County](https://www.overassessed.co/learn/san-mateo-county-property-tax-appeal)
- [How Overassessed compares to other services](https://www.overassessed.co/compare)

## Editorial guarantees

All county facts on this site are sourced from the official County Assessor's office and the California State Board of Equalization. County data fields are versioned in our codebase and reviewed when the county publishes updates.

Overassessed does not provide legal or tax advice. Estimates are based on publicly available data; actual appeal outcomes depend on county review.