Generate a California property tax assessment appeal letter. Challenge over-assessed property values under Prop 13 and Revenue & Taxation Code rules.
Generate My Letter — $19If you own property in California and believe your county assessor has overvalued it, you have a legal right to challenge that assessment. California's property tax system, anchored by Proposition 13, caps annual increases at 2% on a property's base year value—but assessors still make mistakes, miss declines in market value, or improperly trigger reassessments. A well-drafted property tax assessment appeal letter to your County Assessor or Assessment Appeals Board can lead to a reduced assessed value, lower annual tax bills, and refunds for overpayments. Acting quickly matters: California imposes strict filing windows, and missing them generally forfeits your right to appeal for that tax year. This page explains how California law works and how a demand letter fits into the process.
California property taxes are governed primarily by Proposition 13 (1978), codified throughout the Revenue and Taxation Code. Under Prop 13, real property is assessed at its 1975 fair market value or its value at the time of the most recent change in ownership or new construction, with annual inflation adjustments capped at 2% (Cal. Const. art. XIII A; Rev. & Tax. Code § 51). When market values decline below the factored base year value, Proposition 8 (Rev. & Tax. Code § 51(a)(2)) requires the assessor to temporarily reduce the assessed value to current market value. Property owners may challenge assessments on several grounds: (1) the market value on the lien date (January 1) is lower than the assessed value; (2) the property was incorrectly classified or improperly reassessed after a transfer that should have been excluded (such as a parent-child transfer under Prop 19); (3) calculation errors, incorrect square footage, or misidentified improvements; or (4) decline-in-value claims under Prop 8. Appeals are filed with the County Assessment Appeals Board or Board of Equalization under Rev. & Tax. Code § 1603. The filing period runs from July 2 through either September 15 (in counties that mail assessment notices to all owners by August 1) or November 30 (in all other counties). For supplemental or escape assessments, owners have 60 days from the notice date to appeal. The Appeals Board has two years from the filing date to hear and decide the case (§ 1604), and if it fails to do so, the applicant's opinion of value generally becomes the assessed value by default.
Before formally filing Form BOE-305-AH (Application for Changed Assessment), many California property owners send a written appeal or 'Decline-in-Value' request directly to the County Assessor. This informal letter can resolve the dispute without a hearing and preserves a paper trail if escalation becomes necessary. An effective letter identifies the parcel by Assessor's Parcel Number (APN), states the current assessed value, and proposes a supported opinion of value backed by comparable sales (typically three to six recent sales of similar properties near the January 1 lien date), recent appraisals, listing histories, or evidence of physical damage or functional obsolescence. Cite the specific legal basis—Proposition 8 decline-in-value, base year value error under § 51.5, incorrect change-in-ownership determination, or clerical error under § 4831. Demand a specific corrected assessed value and a refund of overpaid taxes with interest under Rev. & Tax. Code § 5151. State clearly that if the Assessor does not respond within a reasonable time (commonly 30 days), you will file a formal Application for Changed Assessment with the Assessment Appeals Board before the statutory deadline. Many assessors will stipulate to a reduction without a hearing when faced with credible market evidence, saving both sides time and expense.
Filing an Assessment Appeals Board application typically costs between $30 and $50, depending on the county; some counties charge no fee. Hearings are conducted before a local Appeals Board or, in some counties, a Hearing Officer for residential properties under a value threshold. The property owner bears the burden of proof, except for owner-occupied single-family homes where the burden shifts to the Assessor (Rev. & Tax. Code § 167). Taxes must still be paid while the appeal is pending to avoid penalties; refunds are issued if you prevail. After an adverse Appeals Board decision, you may file a refund action in California Superior Court within six months under Rev. & Tax. Code § 5141. Small claims court is generally not available for property tax disputes.
Property tax in California is governed by the California Revenue and Taxation Code (property taxation), implementing Article XIII A of the CA Constitution (Proposition 13) (Cal. Const. art. XIII A (Prop 13); Cal. Rev. & Tax. Code §§ 110, 619, 1603, 3691 et seq.). Assessment cycle: Annual lien date of January 1 each year; under Prop 13 the base-year (purchase-price) value is set at acquisition and capped at a maximum 2% inflationary increase per year unless there is a change in ownership or new construction that triggers reassessment. Assessed value: 100% of full cash value (fair market value). Cal. Rev. & Tax. Code § 401 requires assessment at full value. Under Prop 13 the taxable value is the factored base-year value (acquisition value + 2%/yr max), not annual market value.
County Assessor (assessment) and county Assessment Appeals Board / county Board of Equalization (appeals) at the local level; the California State Board of Equalization (BOE) provides statewide oversight, guidance, and property tax rules. The window to act is short — regular assessment appeals filing period runs July 2 through either September 15 or November 30 depending on the county. As of 2025, 11 counties (incl. Alameda, San Francisco, Santa Clara, Ventura) use September 15; the other 47 counties use November 30. Supplemental and escape assessments must be appealed within 60 days of the notice/tax bill mailing date. No extensions.
A recent change to watch: Proposition 19 (passed Nov. 2020; base-year-value transfers effective April 1, 2021) lets homeowners 55+, severely and permanently disabled, or victims of wildfire/disaster transfer their Prop 13 base-year value to a replacement home anywhere in California up to three times, while narrowing the parent-child reassessment exclusion largely to a primary residence the transferee occupies.
Appeal deadline: Regular assessment appeals filing period runs July 2 through either September 15 or November 30 depending on the county. As of 2025, 11 counties (incl. Alameda, San Francisco, Santa Clara, Ventura) use September 15; the other 47 counties use November 30. Supplemental and escape assessments must be appealed within 60 days of the notice/tax bill mailing date. No extensions.
First-level appeal: Application for Changed Assessment filed with the clerk of the county Assessment Appeals Board (AAB), or in smaller counties the county Board of Equalization sitting as the appeals board (Cal. Rev. & Tax. Code § 1603).
Evidence that works: Comparable sales, appraisals, income/expense data (income approach), cost data, and evidence of fair market value as of the valuation date; the § 110(b) rebuttable presumption is that full cash value equals actual purchase price in an open-market transaction.
Next-level appeal: After exhausting the administrative appeal before the Assessment Appeals Board, the taxpayer's further remedy is a refund action in California Superior Court (judicial review), typically after paying the tax and filing a refund claim; there is no intermediate second administrative appeal body.
Grounds you can raise: Assessor's full cash value (fair market value) exceeds actual market value; incorrect base-year value; decline-in-value (Prop 8) below the factored Prop 13 base value; improper change-in-ownership or new-construction reassessment; supplemental or escape assessment disputes.
How your value is assessed: 100% of full cash value (fair market value). Cal. Rev. & Tax. Code § 401 requires assessment at full value. Under Prop 13 the taxable value is the factored base-year value (acquisition value + 2%/yr max), not annual market value.
Exemptions to claim: Homeowners' Exemption: $7,000 reduction in assessed value of an owner-occupied principal residence. Veterans' Exemption: up to $4,000. Disabled Veterans' Exemption: roughly $161,083 basic / $241,627 low-income for 2026 (inflation-adjusted). Property Tax Postponement (age 62+, blind, or disabled) and Prop 19 base-year-value transfers for homeowners 55+, severely disabled, or disaster victims. Prop 13 caps assessed-value growth at 2%/yr.
The hearing: In-person (and increasingly virtual) evidentiary hearing before the county Assessment Appeals Board; taxpayer and assessor present evidence and testimony, and the board renders a value determination.
First, application for Changed Assessment filed with the clerk of the county Assessment Appeals Board (AAB), or in smaller counties the county Board of Equalization sitting as the appeals board (Cal. Rev. & Tax. Code § 1603).
If that fails, after exhausting the administrative appeal before the Assessment Appeals Board, the taxpayer's further remedy is a refund action in California Superior Court (judicial review), typically after paying the tax and filing a refund claim; there is no intermediate second administrative appeal body.
Mind the deadline: regular assessment appeals filing period runs July 2 through either September 15 or November 30 depending on the county. As of 2025, 11 counties (incl. Alameda, San Francisco, Santa Clara, Ventura) use September 15; the other 47 counties use November 30. Supplemental and escape assessments must be appealed within 60 days of the notice/tax bill mailing date. No extensions.
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