Did your California county
reassess you correctly?
Prop 13 protects most homeowners — but errors at purchase, inheritance, and new construction reset your base year value. Those resets are where the mistakes happen.
Average overpayment when reassessment is incorrect: $1,840/year — that's $153/month.
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How Prop 13 Affects Your Appeal Eligibility
Under Proposition 13, California properties are assessed at acquisition value — not annual market value. This protects long-term owners. However, when you purchase a property, complete new construction, or trigger a change-of-ownership under Prop 19, the county resets your base year value. Errors at that reset point can cost you thousands annually — and those errors are appealable to the county's Assessment Appeals Board (AAB).
All 58 California Counties
Select your county to see your local tax rate, average overpayment, and filing options.
Why California Homeowners Get Overcharged Despite Prop 13
Proposition 13 is one of the most powerful property tax protections in the US — it caps annual assessment increases at 2% per year for owners who haven't triggered a reassessment event. Long-term California homeowners pay among the lowest effective rates in the country.
But when a property changes hands, construction is completed, or a Prop 19 transfer occurs, the county resets the base year value to current market value. These resets are error-prone. County assessors frequently value properties based on purchase price without accounting for encumbrances, unusual sale conditions, or market corrections since closing.
California's Assessment Appeals Board (AAB) is an independent body that reviews assessor decisions. Appeals must be filed between July 2 and November 30 of the tax year (some counties close September 15 — check your county clerk). Fairmark handles all AAB filings for $0 today — 25% of first-year savings only if we win.
Assessment cannot go up from a California appeal
An Assessment Appeals Board can only reduce or confirm your assessment — it cannot increase it above what the assessor already set. There is zero risk to checking and filing.
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How California Property Tax Appeals Work
- 1
Identify your reassessment trigger
California appeals typically arise after a purchase, new construction completion, Prop 19 parent-child transfer, or other change-of-ownership event. If your tax bill spiked after any of these events, you may have grounds for an appeal.
- 2
File with the county Assessment Appeals Board (AAB)
Applications must be filed between July 2 and November 30 (some counties close September 15). You'll file AH 305 or your county's equivalent form. Fairmark handles all filings on your behalf.
- 3
Present comparable evidence at your AAB hearing
AAB hearings are informal — you and the assessor each present evidence to a three-member board. Comparable sales from the date of assessment are the strongest evidence. Fairmark prepares the full evidence package.
- 4
Receive your corrected base year value
If the appeal succeeds, your base year value is reduced. Future 2% annual caps apply to the new, lower figure — so the savings compound every year until the next reassessment event.
Your California county is counting on you not checking.
Type your address. See if your reassessment was calculated correctly. Takes 10 seconds. Free.
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