Stanislaus County, home to Modesto and roughly 552k Californians, runs on Proposition 13 (1978) — the constitutional amendment that fundamentally reshaped how California taxes property. Unlike every other state in this almanac, California's property tax base is your purchase price, not the current market value of your home. Two identical homes on the same street can have wildly different tax bills based purely on when they were last sold.
How the bill is built
California's Prop 13 system has four steps. Step 1: Base Year Value (BYV). When you buy a property, the county assessor sets your BYV equal to your purchase price. (For property held continuously since before March 1, 1975, the BYV is the 1975 assessed value — but those parcels are increasingly rare.) Step 2: Factored Base Year Value (FBYV). Each year the BYV grows by the lesser of 2% or the California Consumer Price Index. The 2% cap dominates — for the 2025-26 assessment year, CCPI was 2.514% so the 2% cap applied. Step 3: Taxable Value. From FBYV, subtract the $7,000 Homeowners' Exemption (if owner-occupied) and any Disabled Veterans Exemption. Step 4: Tax. Multiply Taxable Value by the nominal rate for your Tax Rate Area (TRA) — 1% Prop 13 base plus voter-approved bonded indebtedness. For the City of Modesto, this is approximately 1.13%.
2026 Stanislaus County rate breakdown (% of FBYV — applies to new buyers; long-term owners pay this same rate against a lower factored base year value, Modesto district)
| Taxing entity | Rate |
|---|---|
| Stanislaus new-buyer rate (1% Prop 13 + voter bonds) | 1.1300 |
| Combined total | 1.1300 |
As of April 27, 2026 · From Stanislaus County Assessor.
Exemptions, transfers, and Prop 19 for 2026
California's homeowner tax relief works through three mechanisms: (1) the small-but-universal Homeowners' Exemption, (2) the powerful Disabled Veterans Exemption, and (3) the Proposition 19 base-year-value transfer programs for older, disabled, and disaster-affected homeowners. Most of these require a one-time application; once granted, they continue for as long as you qualify.
Homeowners' Exemption — $7,000 reduction in taxable value
If you own and occupy Modesto as your principal residence on January 1 of the tax year, you can claim the Homeowners' Exemption — a $7,000 reduction in taxable value. At the Stanislaus County nominal rate of 1.13%, this saves approximately $79 per year. File Form BOE-266 (also called the Homeowners' Property Tax Exemption Claim) with the Stanislaus County Assessor by February 15 of the year following the lien date. The exemption auto-renews; you only file once.
The Homeowners' Exemption is small in absolute terms compared to the homestead exemptions in Florida, Texas, or Indiana — but every California homeowner-occupant qualifies regardless of income or age, and missing it means leaving roughly $80/year on the table.
Disabled Veterans Exemption — $169,769 to $254,656 reduction
Veterans who are 100% disabled due to a service-connected disability (or whose disability is rated as totally disabling under specific conditions) receive a substantial taxable-value reduction:
- Basic exemption: $169,769 reduction in taxable value (2025 amount; indexed annually for inflation).
- Low-income exemption: $254,656 reduction if household income is below approximately $76,235 (2025 threshold; also indexed annually).
File Form BOE-261-G with the Stanislaus County Assessor. VA disability rating documentation must be attached. Surviving spouses retain the exemption under specific conditions (Revenue and Taxation Code § 205.5).
Proposition 19 (2020) — Base Year Value Transfer
Prop 19 (Article XIII A, Section 2.1, effective April 1, 2021) allows certain homeowners to transfer their existing FBYV to a replacement primary residence anywhere in California. Eligible homeowners include:
- Homeowners aged 55 or older;
- Homeowners who are severely and permanently disabled;
- Homeowners whose home was damaged or destroyed by a wildfire or natural disaster.
The transfer is allowed up to three times in a lifetime (for 55+ and disabled homeowners; unlimited for disaster victims). The replacement home can be of greater value — if so, the FBYV is adjusted upward by the difference between the original and replacement market values. Prop 19 replaced the older Prop 60 / Prop 90 / Prop 110 transfer rules, which were limited to same-county transfers (Prop 60) or specific opt-in counties (Prop 90).
Prop 19 — Inheritance / Intergenerational Transfer
Prop 19 also narrowed the property tax break previously available when parents transferred property to children (formerly Prop 58 / Prop 193). Under the current rules:
- The child must use the inherited property as their primary residence within one year of the transfer to retain any portion of the parent's FBYV.
- The exclusion is capped at $1,044,586 above the prior FBYV (for transfers between February 16, 2025 and February 15, 2027 — the cap is indexed every two years).
- If the home's market value exceeds the parent's FBYV plus the cap, the difference is added to the child's new FBYV.
- Inherited investment properties (rentals, vacation homes) no longer qualify for any exclusion and are reassessed at full market value.
To claim, file Form BOE-19-P (parent-child) or BOE-19-G (grandparent-grandchild) with the county assessor within three years of the transfer date. The child must also file the Homeowners' Exemption (BOE-266) within one year. Missing either deadline means the property is reassessed at full market value with no exclusion.
Appealing your assessment
California's appeal process is shorter than most states but requires careful timing. Your Notice of Assessed Value arrives in July. You have until November 30 in most counties (September 15 in counties that mail notices early) to file Form BOE-305-AH (Application for Changed Assessment) with the County Assessment Appeals Board.
Note that California's Prop 13 acquisition-value system means appeals are most useful in two specific scenarios: (1) Prop 8 temporary reductions — if your home's current market value has fallen below your FBYV (e.g., during a real-estate downturn), you can request a temporary reduction to market value; (2) change in ownership disputes — challenging the assessor's determination of when (or whether) a reassessable change in ownership occurred. General disagreements with valuation methodology are less effective in California than in market-value states because the FBYV is anchored to a specific historical purchase price.
If unresolved through the local Assessment Appeals Board, the next step is California Superior Court (which can review only on questions of law, not factual valuation). The Stanislaus County Assessor maintains the appeal forms and hearing schedule.