Rob Hartley

Founder, AppealDesk · February 16, 2026

California Prop 13: Property Tax Appeal Guide

Updated February 2026 · 12 min read

How Proposition 13 Works

Passed by California voters in 1978, Proposition 13 fundamentally changed how California assesses property. Three core rules:

1. 1% tax rate cap: Your base property tax rate cannot exceed 1% of assessed value. Additional voter-approved bonds and special assessments add 0.1-0.5% in most areas, bringing total effective rates to roughly 1.1-1.5%.
2. 2% annual increase cap: Your assessed value can increase by a maximum of 2% per year (the “inflation factor”), regardless of how much market values actually increase. In hot markets, this creates a growing gap between assessed value and market value.
3. Reassessment on change of ownership or new construction: When a property is sold or undergoes new construction, the assessor resets the assessed value to current market value. This new value becomes the “base year value” for future 2% annual increases.

For a complete breakdown of how the 2% cap works, including base year value transfers and Proposition 19 changes, see our detailed guide on how much property taxes can increase in California.

When Can You Appeal Under Prop 13?

Prop 13 limits how much your assessment can increase, but it doesn’t prevent you from challenging an assessment that’s too high. You have grounds to appeal in these situations:

1. Prop 8 Decline-in-Value

If your home’s current market value drops below your Prop 13 factored base year value (base year value + cumulative 2% annual increases), you can file a Proposition 8 decline-in-value claim. The assessor will temporarily reduce your assessed value to current market value.

This happens during market downturns. After the 2008 housing crisis, millions of California homeowners received Prop 8 reductions. It can also apply locally — if your specific neighborhood has seen value declines due to environmental issues, nearby development, or other factors, even while the broader market is stable.

Important: A Prop 8 reduction is temporary. When market values recover, the assessor will increase your assessed value back toward your Prop 13 base year value (plus accumulated 2% increases). The assessed value won’t exceed the Prop 13 cap — it just won’t stay at the Prop 8 reduced level permanently.

2. Incorrect Base Year Value

If you believe the assessor set your base year value too high when you purchased your home (or after new construction), you can challenge it. This is most common when the purchase involved unusual terms — seller concessions, non-arm’s-length transactions, or properties that needed significant repair at the time of purchase.

3. Property Description Errors

Incorrect square footage, lot size, room count, or other physical characteristics that inflate your base year value. These errors compound over time through the 2% annual factor.

How to File a California Property Tax Appeal

Step 1: Determine Your Factored Base Year Value

Look up your property on your county assessor’s website. Find your base year value and the current factored value (base + cumulative 2%). This is the ceiling for your Prop 13 assessment. If the current assessed value equals this ceiling and current market value is above it, your assessment is correct under Prop 13 — no appeal is possible.

Step 2: Research Current Market Value

Find 3-5 comparable sales — recent arm’s-length sales of similar properties within your neighborhood. California uses a 100% assessment ratio, so sale prices compare directly to assessed values. See our guide on finding comparable sales. Sources include your county assessor’s website, Zillow (sold listings, not Zestimates), Redfin, and Realtor.com.

Step 3: File the Application for Changed Assessment

File with your county’s Assessment Appeals Board (also called the Board of Equalization in some counties). Use the Application for Changed Assessment form, available from your county assessor’s website. Key details:

• Filing window: July 2 through September 15 in most counties; some counties extend to November 30. Check your specific county.
• Required information: Your property’s parcel number (APN), the current assessed value, your opinion of market value, and the basis for your claim.
• Evidence to include: Comparable sales data, photos of condition issues, property description corrections, and any professional analysis.

Step 4: Attend the Assessment Appeals Board Hearing

After filing, you’ll be scheduled for a hearing before the Assessment Appeals Board (typically a 3-member panel). Present your comparable sales, condition documentation, and any other evidence. The board issues a decision that’s binding unless you appeal to Superior Court. Many counties in California are backlogged, so hearings may be scheduled 6-18 months after filing. For hearing preparation, see our hearing guide.

Proposition 19: Transferring Your Base Year Value

Effective April 1, 2021, Proposition 19 allows eligible homeowners to transfer their Prop 13 base year value to a replacement home anywhere in California:

• Eligible homeowners: Age 55+, severely disabled, or victims of wildfire/natural disaster
• No county restriction: You can move from any county to any other county in California
• Any-value replacement: If the new home costs more, only the difference above your old home’s market value is added to your transferred base year value
• Up to 3 transfers: You can use this provision up to three times in your lifetime
• 2-year window: You must buy the replacement home within two years of selling the original (before or after the sale)

Prop 19 also changed parent-child transfers: the exclusion from reassessment now only applies when the child uses the property as their primary residence, and only the first $1 million of value above the factored base year value is excluded.

Major California Counties: Appeal Details

California Property Tax Appeal Services

Several services handle California property tax appeals:

• AppealDesk: $49 flat fee for evidence packet with comparable sales and filing guide for any California county. You file yourself.
• Ownwell: Full-service at 25-35% of savings. Covers California as one of their 9 states.
• O’Connor: Full-service at a percentage of savings. Covers California through their national network.

On a $3,000 annual reduction (common in California’s high-value market), AppealDesk costs $49 while Ownwell costs $750-1,050. See our AppealDesk vs Ownwell comparison for details. For more options, see our best property tax appeal services comparison. For cost details, see how much a property tax appeal costs.

Frequently Asked Questions