Does Proposition 13 cap apply to the property tax bill itself, or just the rate?

Just the rate cap (1% of assessed value) and the annual-increase cap (2% on assessed value). The total property tax bill can exceed 1% of current market value once voter-approved bonds, Mello-Roos special taxes, and other special assessments are added. The "1%" is a cap on the ad valorem tax rate, not on the total tax bill.

Does Prop 13 protect rental property the same way as a primary residence?

Yes — the Prop 13 framework applies to all real property regardless of use. Rental properties, vacation homes, commercial property, and primary residences all get the 1% rate cap, the 2% annual increase cap, and the base-year-value protection. The Prop 19 changes did narrow the parent-child transfer exclusion to primary residences only, but the underlying Prop 13 framework treats all property types similarly during the owner's holding period.

What is the "base year value" and how is it set?

The base year value is the property's fair market value on the date of acquisition (the change of ownership) or completion of new construction. It serves as the starting point for the Prop 13 calculation, with the 2% annual increase cap applied each subsequent year. For property owned before March 1, 1975 (the Prop 13 base date), the base year value is the 1975–76 assessment. For property acquired after Prop 13's passage, the base year value is the purchase price (or, in the case of gifts and other non-arm's-length transfers, the fair market value at the date of transfer).

How did Proposition 19 change the parent-child transfer exclusion?

Prop 19 narrowed it substantially. The former exclusion allowed parents to transfer their primary residence and up to $1 million of assessed value in other property to children without reassessment. The new exclusion is limited to the primary residence and only if the transferee child uses it as the child's primary residence within one year. If the property's fair market value exceeds the transferred base year value by more than $1 million (as biennially adjusted under Prop 19 and BOE guidance), the assessed value is increased. Transfers of non-primary residences (rental property, vacation homes) from parent to child are no longer excluded and trigger full reassessment.

What is the supplemental tax bill?

A separate tax bill issued mid-fiscal-year when a property changes ownership or completes new construction. The seller paid the regular annual tax bill based on the prior assessment; the buyer's reassessment produces a supplemental bill covering the additional tax for the months between acquisition and the end of the fiscal year, plus a new annual bill going forward at the reassessed value. Many buyers are surprised by the supplemental bill because it arrives separately from the regular annual property tax bill, often months after acquisition.

Can a homeowner appeal a property tax assessment?

Yes. Homeowners can file an application with the county assessor for a Prop 8 temporary downward reassessment when market value falls below assessed value, or file a formal assessment appeal with the county Assessment Appeals Board (or equivalent) challenging the assessor's valuation. Appeal procedures and deadlines are set by Rev. & Tax. Code §1601 et seq. and vary somewhat by county. Most appeals must be filed within a defined window (often July 2 to September 15 or November 30, depending on the county).

Proposition 13 and California Property Tax Assessment

TL;DR

Proposition 13 — passed by California voters in June 1978 and codified as Article XIII A of the California Constitution — fundamentally restructured California property taxation. The framework caps the ad valorem property tax rate at 1% of assessed value, caps annual increases in assessed value at 2% (or the inflation rate, whichever is lower), and locks assessed value to the purchase price ("base year value") at the time of acquisition or new construction. Reassessment occurs only on a change of ownership or new construction. Proposition 8 (also 1978) permits temporary downward reassessment when market value falls below assessed value. Proposition 19 (passed November 2020, effective February 2021) significantly narrowed the parent-child transfer exclusion and expanded the base-year-value transfer right for seniors, disabled persons, and disaster victims. For the broader California exam framework, see our California real estate exam guide.

The Prop 13 framework — three core caps

Proposition 13's substantive structure rests on three statutory caps. First, the tax rate cap: California Constitution Article XIII A §1 limits the ad valorem property tax to 1% of the property's assessed value. Local taxing entities (counties, cities, school districts, special districts) collectively cannot levy more than 1% in ad valorem property tax, though voter-approved indebtedness (general obligation bonds passed before 1978 or after by qualifying supermajorities) can add to this base rate. Second, the annual increase cap: Article XIII A §2(b) limits annual increases in assessed value to 2% per year, or the change in the California Consumer Price Index for the prior year, whichever is lower. Third, the base year value: the assessed value is set at the property's fair market value on the date of acquisition (or completion of new construction), then carried forward subject to the 2% annual cap.

The combined effect is that long-time California homeowners often pay property taxes on assessed values dramatically below current market values. A homeowner who acquired property in 1985 at $200,000 may have an assessed value below $500,000 today, even when the property's current market value exceeds $2 million. The Prop 13 framework intentionally produces this disparity to protect long-time owners from tax-driven displacement — but the structural effect also creates substantial intergenerational and intracommunity inequities.

Reassessment triggers — change of ownership and new construction

Two events trigger reassessment of California real property: a change of ownership and new construction. Change of ownership generally includes most transfers of beneficial ownership — sales, gifts, inheritances (subject to exclusions), and transfers between certain entities. Some transfers are statutorily excluded from "change of ownership" treatment under Rev. & Tax. Code §62, including transfers between spouses, transfers into and out of revocable trusts (with the transferor as the trustor), and certain inter-spousal transfers incident to divorce.

New construction reassessment under Rev. & Tax. Code §70 applies to additions, improvements, and major remodels. A homeowner who adds a 500-square-foot family room or constructs a swimming pool faces reassessment of the new construction (not the entire property) at the new construction's fair market value, while the original portion retains its existing base year value. Routine maintenance, repairs, and like-for-like replacements (replacing a roof with a similar roof) typically do not trigger reassessment.

The supplemental tax bill mechanism under Rev. & Tax. Code §75 handles reassessments occurring mid-fiscal-year. When a property changes ownership in March, the seller had paid taxes based on the prior assessment for the July-to-July fiscal year. The buyer's reassessment produces a supplemental tax bill for the months from acquisition through the end of the fiscal year, plus a new annual bill at the reassessed value going forward. Many buyers are surprised by the supplemental tax bill — it arrives separately from the regular annual property tax bill and reflects the prorated additional tax for the partial year.

Proposition 8 — the temporary downward reassessment

Proposition 8 (also approved by voters in 1978) amended Article XIII A to require temporary downward reassessment when a property's market value falls below its Proposition 13 assessed value. The mechanism protects homeowners during market downturns: when home values fall, the assessor must reduce the assessed value to the current market value, producing a corresponding reduction in property taxes. When market values recover, the assessor can increase the assessed value back toward the original Prop 13 base year value plus accumulated 2% increases — but the assessed value cannot exceed what the Prop 13 framework would have produced if no temporary reduction had occurred.

Prop 8 reassessments were widely used during the 2008–2012 housing downturn, when California home values fell substantially from 2007 peaks. Many homeowners filed Prop 8 applications with their county assessor seeking temporary downward reassessment. When the market recovered, the assessors raised assessed values back to the Prop 13 trajectory — but the temporary tax relief during the downturn was a meaningful homeowner benefit.

Proposition 19 — the 2020 changes

Proposition 19, passed by California voters in November 2020 and effective February 2021 (parent-child changes) and April 2021 (base-year transfer changes), made two significant amendments to the Prop 13 framework. The parent-child transfer exclusion under former Article XIII A §2(h) and Rev. & Tax. Code §63.1 — which had allowed parents to transfer their primary residence and up to $1 million of assessed value in other property to children without triggering reassessment — was substantially narrowed.

Under Prop 19, the parent-child exclusion is now limited to a primary residence that the transferee child uses as the child's own primary residence within one year of the transfer. The transferee child must file a homeowner's exemption claim within one year. If the property's fair market value exceeds the transferred base year value by more than $1 million (as biennially adjusted under Prop 19 and BOE guidance), the assessed value is increased by the excess. The former exclusion for non-primary residence parent-child transfers (rental properties, vacation homes) was eliminated entirely — those transfers now trigger full reassessment.

The other Prop 19 change expanded the base-year-value transfer right for qualifying homeowners. Seniors 55 or older, severely disabled persons, and victims of natural disasters or hazardous waste contamination can now transfer their existing base year value to a replacement primary residence anywhere in California, up to three times during their lifetime. The replacement home can be of equal or greater value (with the value differential added to the transferred base year value); the prior Article XIII A §2(a) "equal or lesser value" restriction was eliminated. The base-year transfer must be completed within two years of the sale of the prior primary residence.

Mello-Roos and special assessments

Proposition 13's 1% rate cap does not include voter-approved special taxes and assessments. Mello-Roos Community Facilities Districts (created under the Mello-Roos Community Facilities Act of 1982, Gov. Code §53311 et seq.) impose special taxes on properties within a defined district to fund infrastructure, schools, and public services. These taxes appear on the property tax bill separately from the 1% Prop 13 rate and can substantially increase total annual property tax. New housing developments may carry substantial Mello-Roos obligations for the bond repayment period, often lasting decades.

Special taxes and assessments under various state and local authorities also produce additional charges on the property tax bill. Cross-reference matters because the Prop 13 1% rate is only the start of the tax calculation — buyers in newer developments or specially-assessed areas can face total property tax burdens significantly higher than the 1% Prop 13 base rate would suggest. The seller's Transfer Disclosure Statement and the buyer's title report should reflect any Mello-Roos or special assessment obligations.

Cross-state comparison

California's Proposition 13 framework has parallels in other states but is structurally distinctive. Florida's Save Our Homes amendment (Article VII §4 of the Florida Constitution) caps annual assessment increases on homesteaded property at 3% or the CPI change (whichever is lower), with a $500,000 portability provision allowing homeowners to transfer accrued SOH benefit to a new homestead. Texas's homestead protection under Article XVI §§50–51 focuses primarily on creditor protection rather than property-tax limitation, with separate statutory homestead exemptions reducing taxable value.

California's approach differs structurally: where Florida caps assessment increases on the homestead but reassesses on transfer, California caps all property's assessed value to purchase price + 2% annual growth, regardless of homestead status. Texas's homestead framework focuses primarily on creditor protection rather than tax limitation. California's 1% rate cap is also lower than the effective property tax rates in many other large states. The result is that California property taxes, viewed as a percentage of current market value, are often substantially lower for long-time owners than the headline 1% rate would suggest.

Frequently Asked Questions

Does Proposition 13 cap apply to the property tax bill itself, or just the rate?: Just the rate cap (1% of assessed value) and the annual-increase cap (2% on assessed value). The total property tax bill can exceed 1% of current market value once voter-approved bonds, Mello-Roos special taxes, and other special assessments are added. The "1%" is a cap on the ad valorem tax rate, not on the total tax bill.
Does Prop 13 protect rental property the same way as a primary residence?: Yes — the Prop 13 framework applies to all real property regardless of use. Rental properties, vacation homes, commercial property, and primary residences all get the 1% rate cap, the 2% annual increase cap, and the base-year-value protection. The Prop 19 changes did narrow the parent-child transfer exclusion to primary residences only, but the underlying Prop 13 framework treats all property types similarly during the owner's holding period.
What is the "base year value" and how is it set?: The base year value is the property's fair market value on the date of acquisition (the change of ownership) or completion of new construction. It serves as the starting point for the Prop 13 calculation, with the 2% annual increase cap applied each subsequent year. For property owned before March 1, 1975 (the Prop 13 base date), the base year value is the 1975–76 assessment. For property acquired after Prop 13's passage, the base year value is the purchase price (or, in the case of gifts and other non-arm's-length transfers, the fair market value at the date of transfer).
How did Proposition 19 change the parent-child transfer exclusion?: Prop 19 narrowed it substantially. The former exclusion allowed parents to transfer their primary residence and up to $1 million of assessed value in other property to children without reassessment. The new exclusion is limited to the primary residence and only if the transferee child uses it as the child's primary residence within one year. If the property's fair market value exceeds the transferred base year value by more than $1 million (as biennially adjusted under Prop 19 and BOE guidance), the assessed value is increased. Transfers of non-primary residences (rental property, vacation homes) from parent to child are no longer excluded and trigger full reassessment.
What is the supplemental tax bill?: A separate tax bill issued mid-fiscal-year when a property changes ownership or completes new construction. The seller paid the regular annual tax bill based on the prior assessment; the buyer's reassessment produces a supplemental bill covering the additional tax for the months between acquisition and the end of the fiscal year, plus a new annual bill going forward at the reassessed value. Many buyers are surprised by the supplemental bill because it arrives separately from the regular annual property tax bill, often months after acquisition.
Can a homeowner appeal a property tax assessment?: Yes. Homeowners can file an application with the county assessor for a Prop 8 temporary downward reassessment when market value falls below assessed value, or file a formal assessment appeal with the county Assessment Appeals Board (or equivalent) challenging the assessor's valuation. Appeal procedures and deadlines are set by Rev. & Tax. Code §1601 et seq. and vary somewhat by county. Most appeals must be filed within a defined window (often July 2 to September 15 or November 30, depending on the county).

Bottom Line

Proposition 13 under California Constitution Article XIII A is the foundational property tax framework: 1% rate cap, 2% annual increase cap on assessed value, and base year value locked to acquisition price. Reassessment occurs only on change of ownership or new construction; Proposition 8 permits temporary downward reassessment in market downturns; Proposition 19 (2020) narrowed the parent-child transfer exclusion and expanded base-year-value transfers for seniors, disabled persons, and disaster victims. Mello-Roos special taxes and other special assessments operate alongside the 1% Prop 13 rate and can substantially increase total property tax. The supplemental tax bill captures the prorated additional tax when a property changes ownership mid-fiscal-year. For the broader California exam framework, see our California real estate exam guide. For comparable property-tax frameworks in other states, see our Florida Save Our Homes guide and our Texas constitutional homestead guide.

Source: Cal. Const. Article XIII A — Tax Limitation (Proposition 13) · Cal. Rev. & Tax. Code Div. 1 — Property Taxation · California Board of Equalization — Property Tax Resources