California property tax law is built around Proposition 13, a 1978 constitutional amendment that caps the base tax rate at 1% of a property’s assessed value and limits annual increases in that assessed value to 2%. Voter-approved bonds, Mello-Roos taxes, and special assessments get added on top, which is why most homeowners actually pay somewhere between 1.1% and 1.5% of assessed value. The system rewards long ownership and punishes surprises: certain events reset your assessment to current market value overnight, and the tax bill can jump accordingly.
The 1% Base Rate and How Your Assessed Value Is Set
Article XIII A of the California Constitution caps the ad valorem property tax rate at 1% of a property’s full cash value.1Justia. California Constitution Article XIII A Section 1 – Tax Limitation That 1% flows to the county, which distributes it among local agencies, schools, and special districts. The cap does not cover voter-approved bond debt for schools or infrastructure, which is added separately.2California Legislative Information. California Constitution – Article XIII A – Tax Limitation
When you buy a property, the county assessor sets a base year value equal to the purchase price. That figure becomes the starting point for every future tax bill for as long as you own the property. The practical result is striking for long-term owners. A house bought in 1990 might still carry an assessed value of $250,000 even though it would sell today for $1.2 million. The buyer next door, who closed last month, pays taxes on the full purchase price.
The 2% Annual Cap on Assessment Growth
Each year the assessor adjusts your base year value upward by the change in the California Consumer Price Index, and the increase cannot exceed 2%.3Justia. California Constitution Article XIII A Section 2 – Tax Limitation When inflation runs hotter than 2%, the cap kicks in and your assessed value rises by exactly 2%. In lower-inflation years, the increase can be smaller. For the 2025–26 fiscal year, the statewide CCPI change was about 2.5%, so the inflation factor applied to assessed values was the full 2%.4California State Board of Equalization. California Property Tax An Overview
What Triggers a Full Reassessment
Two events break through the Proposition 13 cap and reset your assessed value to current market: a change in ownership and new construction.
Change in Ownership
Revenue and Taxation Code Section 60 defines a change in ownership as a transfer of a present interest in real property where the value transferred is substantially equal to the fee interest.5California Legislative Information. California Revenue and Taxation Code – Implementation of Article XIII A A standard home sale is the obvious trigger, but transfers of controlling interests in entities that own property can also count. When the assessor identifies a change in ownership, the property gets a brand-new base year value at current market price. The new owner’s Proposition 13 protections start fresh from there.
New Construction
Adding square footage, converting a garage into living space, or performing a major renovation that produces the equivalent of a new structure all count as new construction under Revenue and Taxation Code Section 70.6California Legislative Information. California Revenue and Taxation Code RTC 70 – New Construction The assessor values only the new or altered portion at current market rates. The existing structure keeps its capped assessed value. Add a second story to a home with a $300,000 assessed value, and you pay taxes on that $300,000 (plus inflation adjustments) for the original portion, plus whatever the addition is worth today.
One important exception: if your home is damaged by fire, earthquake, or another disaster and you rebuild to substantially the same condition, the reconstruction is not treated as new construction and does not trigger a reassessment.6California Legislative Information. California Revenue and Taxation Code RTC 70 – New Construction Ordinary maintenance and repair also do not trigger reassessment.
Supplemental Tax Bills After a Purchase
New homeowners are often caught off guard by supplemental tax bills that arrive months after closing. When a change in ownership or new construction resets the assessed value, the assessor calculates the difference between the old assessed value and the new one, then charges a prorated amount for the remaining months in the fiscal year (July 1 through June 30).7California State Board of Equalization. Supplemental Assessment
The timing of your purchase determines how many supplemental bills you receive. A purchase between June 1 and December 31 produces one supplemental bill covering the rest of the current fiscal year. A purchase between January 1 and May 31 produces two: one for the remainder of the current fiscal year and one for the full next fiscal year.8California Legislative Information. California Revenue and Taxation Code 75.11 These bills are separate from your regular annual tax bill and are not covered by your mortgage escrow account unless you specifically arrange it. Budget for them.
Parent-to-Child Transfers Under Proposition 19
Before February 2021, parents could pass any property to their children without triggering a reassessment. Proposition 19 narrowed that benefit sharply. Under Revenue and Taxation Code Section 63.2, a parent-to-child transfer now avoids reassessment only if the property was the parent’s primary residence and the child makes it their own primary residence within one year of the transfer.9California Legislative Information. California Revenue and Taxation Code RTC 63.2 – Change in Ownership Exclusion
Even when those conditions are met, the exclusion has a dollar cap. If the property’s fair market value at the time of transfer exceeds the existing factored base year value by more than $1 million, the excess gets added to the tax roll. Suppose the parent’s assessed value is $200,000 and the home’s market value is $1.5 million. The gap is $1.3 million. The first $1 million is excluded, but the remaining $300,000 is added to the new assessed value, making the child’s taxable value $500,000 rather than $1.5 million.9California Legislative Information. California Revenue and Taxation Code RTC 63.2 – Change in Ownership Exclusion
Grandparent-to-grandchild transfers qualify only if the middle generation (the grandchild’s parents) are deceased at the time of the transfer.9California Legislative Information. California Revenue and Taxation Code RTC 63.2 – Change in Ownership Exclusion Investment properties, vacation homes, and rentals transferred between generations no longer receive any exclusion under Proposition 19.
Moving and Keeping Your Assessment: Base Year Value Transfers
Proposition 19 also expanded portability for certain homeowners. If you are 55 or older, severely and permanently disabled, or you lost your home in a governor-declared disaster, you can transfer the assessed value from your old primary residence to a new one anywhere in California. The limit is three transfers per lifetime, and disaster victims get one transfer per disaster.10California State Board of Equalization. Proposition 19
Two deadlines matter. You must purchase or complete construction of the replacement home within two years of selling the original.11Los Angeles County Assessor. Proposition 19 And you must file the claim with the county assessor within three years of purchase or completion to receive the full retroactive benefit. File later than that and relief runs only forward from the filing date.10California State Board of Equalization. Proposition 19
If the replacement home costs more than the original, the assessor adds the difference to your transferred base year value. If it costs the same or less, you carry over the old assessed value without adjustment. Before Proposition 19, portability was limited to moves within the same county or to a handful of participating counties. That geographic restriction is gone.
Exemptions That Reduce Your Assessed Value
Homeowners’ Exemption
Every owner-occupied primary residence qualifies for a $7,000 reduction in assessed value under Article XIII, Section 3(k) of the California Constitution.12Justia. California Constitution Article XIII Section 3 – Taxation At a 1% base rate, that saves about $70 a year. Modest, but there is no income test and no need to reapply after the initial filing. You must occupy the home as your principal residence on January 1 (the lien date) to qualify for that year.13California Legislative Information. California Revenue and Taxation Code RTC 2192 The exemption ends automatically when you sell or stop using the home as your primary residence.
Disabled Veterans’ Exemption
Veterans with a 100% service-connected disability rating, or those rated unemployable at the 100% compensation level, qualify for a substantially larger exemption on their primary residence. For the 2026 lien date, the basic exemption is $180,671 off the assessed value, available regardless of income. The low-income exemption is $271,009 off the assessed value, available when the household’s prior-year income falls below an annually adjusted threshold.14California State Board of Equalization. Disabled Veterans Exemption Increases for 2026 Both amounts are adjusted each year for inflation. Unmarried surviving spouses of eligible veterans may also claim the exemption.
Mello-Roos and Special Assessments
Your tax bill often carries charges beyond the 1% base rate and voter-approved bonds. The two most common are Mello-Roos special taxes and special assessments, and together they can add thousands of dollars a year, especially in newer subdivisions.
A Mello-Roos tax comes from a Community Facilities District created under the Mello-Roos Community Facilities Act of 1982.15California Legislative Information. California Government Code 53311 – Mello-Roos Community Facilities Act of 1982 Property owners in a defined area vote to impose a special tax to fund infrastructure like roads, sewers, schools, and parks. Unlike the base property tax, a Mello-Roos charge is not tied to your property’s assessed value. It might be calculated per square foot, per dwelling unit, or by some other formula specific to the district.
Special assessments are legally distinct. They fund specific improvements that directly benefit a defined area, and the charge must be proportional to the benefit each parcel receives. Both Mello-Roos taxes and special assessments show up as line items on your annual property tax bill and are collected alongside the regular property tax. When buying a home, check the full tax bill for these charges. In some newer communities they push the effective tax rate well above 2%.
Payment Deadlines and Late Penalties
Property taxes on the secured roll are paid in two installments each fiscal year.16California State Board of Equalization. Property Tax Calendar The first installment is due November 1 and delinquent after 5:00 p.m. on December 10. The second is due February 1 and delinquent after 5:00 p.m. on April 10. If a delinquency date falls on a weekend or holiday, it extends to the next business day.
Missing either deadline triggers a 10% penalty on the unpaid installment.17California Public Law. California Revenue and Taxation Code Section 2618 On a $5,000 installment, that is an immediate $500 charge with no grace period.
If any amount remains unpaid by June 30, the property becomes tax-defaulted. Additional penalties accrue at 1.5% per month on the unpaid balance, and a redemption fee is added. To clear the default you must pay all delinquent years together; you cannot pick and choose. After five years in default, the county gains the power to sell the property to recover the unpaid taxes under Revenue and Taxation Code Section 3691.18State Controller’s Office. Notice of Power to Sell Tax Defaulted Property Tax sales are not theoretical; counties conduct them regularly.
Deferring Payments: Property Tax Postponement
The State Controller’s Office runs a program that lets seniors 62 and older, blind individuals, and people with disabilities defer property tax payments until they sell the home, move out, or pass away. For the 2025–26 program year, the household income limit is $55,181, and you need at least 40% equity in the home.19State Controller’s Office. Property Tax Postponement The state pays your taxes and places a lien on the property for the deferred amount, which accrues interest and must be repaid when the home changes hands.
When Your Home Is Worth Less Than the Assessment
If the market drops and your property’s current market value falls below its assessed value, you may be entitled to a temporary reduction, commonly called a Proposition 8 reduction. The assessor is supposed to enroll the lower of the factored base year value or the current market value as of the January 1 lien date.20California State Board of Equalization. Decline in Value – Proposition 8
In practice, the assessor may not catch every property that qualifies. Many counties allow an informal decline-in-value review through the assessor’s office, and you always retain the right to file a formal assessment appeal. Once a property receives a Prop 8 reduction, the assessor reviews it each year. As the market recovers, your assessed value can rise by more than 2% per year until it reaches the original factored base year value. Only then does the normal 2% annual cap take over again. Homeowners who grew comfortable with a lower bill during a downturn are often surprised by that catch-up.
Filing an Assessment Appeal
If you believe your property’s assessed value exceeds its market value and the assessor has not made the adjustment, you can file a formal appeal by submitting an Application for Changed Assessment to the Clerk of the Board of Supervisors in your county.21California State Board of Equalization. Application for Changed Assessment
The regular filing window opens July 2. The closing date depends on whether your county assessor mails assessment notices to all secured-roll taxpayers by August 1. If notices are mailed by then, the deadline is September 15. If not, the window runs through November 30 (or the next business day if that date falls on a weekend).22California State Board of Equalization. California State Board of Equalization Letter to County Assessors No. 2025/020 Miss the deadline and you lose the right to challenge that year’s assessment.
The strongest appeals include comparable sales data: recent sales of similar homes near the January 1 lien date, adjusted for differences in size, location, condition, and lot. Three to five well-chosen comparables carry more weight than a dozen loosely related ones. An Assessment Appeals Board or hearing officer weighs your evidence against the assessor’s and issues a written decision. Appeals are not risk-free; the board can raise your assessment if the evidence supports a higher value than what was on the roll.