Thinking about a move within Contra Costa or from Alamo to another California city, but worried about a big jump in property taxes? If you qualify under Prop 19, you may be able to transfer much of your current taxable value to your next primary home. That can help you rightsize your life without an outsized tax bill.
In this guide, you’ll learn who qualifies, how the timing works, how assessors calculate your new taxable value, and what to do first in Contra Costa County. You’ll also see common pitfalls and where to find official, up-to-date answers. Let’s dive in.
What Prop 19 changed
Prop 19 is a 2020 California constitutional amendment that reshaped how certain property tax transfers work. It expanded portability for eligible homeowners so you can move your taxable (base) value to a replacement primary residence anywhere in California. It also narrowed older rules for transfers between parents and children.
County assessors, including Contra Costa, administer claims and calculate reassessments under these rules. For a statewide overview and FAQs, visit the California State Board of Equalization’s Prop 19 guidance on the BOE website.
Who qualifies in Contra Costa
You may be eligible to transfer your taxable value if, at the time of transfer, you meet one of these categories:
- You are age 55 or older.
- You are severely disabled.
- You are a victim of wildfire or another natural disaster and were displaced.
These rules apply to your primary residence only, and the replacement property must also be your primary residence. For official voter-approved language and summaries, review the Proposition 19 materials in the California Voter Information Guide.
How many times and where you can move
Under Prop 19, eligible homeowners can transfer their base value multiple times, up to a statutory limit. For most age 55 or severely disabled homeowners, that limit is commonly cited as up to three transfers. Intercounty moves are allowed statewide, so you can move within Contra Costa or to any other California county.
There are special provisions for disaster-related claims and implementation details that may affect counts or timing. For local guidance, start with the Contra Costa County website and navigate to the Assessor’s Office resources.
Timing rules you need to know
The replacement primary residence generally must be purchased or newly constructed within a limited timeframe relative to the sale of your original home. A commonly applied window is up to two years before or up to two years after the sale of the original property. Filing deadlines and exact timing can vary, so confirm current requirements with the Contra Costa County Assessor.
If you prefer to buy first and sell later, or sell first and take time to buy, this two-year window can make portability possible as long as you meet filing and date requirements.
How your new taxable value is calculated
The assessor compares the market value of your replacement home to the market value of your original home at the time of transfer. Then they apply one of two paths:
- If the replacement’s market value is equal to or less than your original home’s market value, your original taxable value generally carries over.
- If the replacement’s market value is higher, your new assessed value is typically your original taxable value plus the difference in market value between the two homes.
In simple terms: New assessed value ≈ original taxable value + (replacement market value − original market value). Assessors also consider supplemental assessments and timing, so expect some administrative adjustments.
What counts as a primary residence
Prop 19 transfers apply to principal residences. That means the home you live in as your primary residence. Vacation homes and strictly investment properties are not eligible.
Your replacement property can be a single-family home, condo, or manufactured home, so long as it will be your principal residence. For many downsizers in Alamo and nearby communities, moving to a smaller home or condo is fully compatible with the rules.
Downsizing and relocating scenarios
Because Alamo and nearby Contra Costa markets have higher home values, transferring your taxable value can lead to meaningful savings. Here are two simple illustrations to show how the math can work. These are examples only. Always confirm your situation with the Contra Costa County Assessor.
- Downsizing example (illustrative): You sell an Alamo home with a market value of $2,000,000 and a low taxable value. You buy a $1,200,000 condo in Contra Costa. Because the replacement’s market value is lower, your taxable value may carry over, helping you avoid a full reassessment to current market levels.
- Buying higher example (illustrative): You sell a home with a market value of $1,600,000 and buy a $1,900,000 replacement. Your new assessed value would typically be your original taxable value plus the $300,000 difference in market value. You may see some increase, but often less than if the entire home were reassessed at current market value.
Multiple moves may be possible if you qualify, which can help you plan a step-by-step transition closer to family, medical care, or a simpler lifestyle.
Filing steps in Contra Costa
Here is a practical roadmap to keep your move on track:
- Plan early
- Contact the Contra Costa County Assessor’s Office before you close on your sale or purchase to confirm eligibility and forms. Start at the County’s website and navigate to the Assessor’s page for contacts and instructions.
- Gather documents
- Recorded deed or preliminary title information for both properties.
- Closing statements showing dates and prices for sale and purchase.
- Proof of age (driver’s license or birth certificate), or disability documentation if applicable.
- Evidence of disaster displacement if you are claiming under that category.
- File the claim
- Obtain the county’s claim form for transfer of base year value. File it as soon as possible following county guidance.
- Ask your escrow officer, title company, or real estate agent for help assembling paperwork. The assessor makes the final determination.
- Confirm deadlines
- Filing timelines can be strict. Confirm the current deadline and any supplemental steps with the Contra Costa Assessor.
Avoid these common pitfalls
- Missing the two-year timing window for purchase or new construction relative to your sale.
- Forgetting that the property must be your principal residence. Turning it into a rental or vacation property may affect your transfer.
- Assuming intercounty moves are restricted. Prop 19 allows moves anywhere within California, but filing occurs in the county of the replacement property.
- Overlooking supplemental assessments if you build new or complete major additions.
What about family transfers?
Prop 19 narrowed older parent-child and grandparent-grandchild exclusions. Today, these exclusions are more limited and generally apply only when the child will occupy the property as a principal residence, with value limitations and adjustments. This area can be complex, especially for inherited property.
For clear definitions and voter-approved language, see the Proposition 19 section of the California Voter Information Guide. For implementation guidance and FAQs, check the California BOE. You can also look up the current statutes and amendments on California Legislative Information.
Planning tips and local support
- Start early with the Contra Costa Assessor to understand forms, dates, and how your scenario will be calculated.
- Keep thorough records from escrow and title so your claim is complete the first time.
- If your situation involves inheritance, trusts, or complex tax planning, consult a qualified tax or estate professional. The assessor has final authority on your assessment outcome.
If you want a warm, local guide for your next move, especially within Rossmoor or nearby Walnut Creek-area neighborhoods, reach out. I can help you plan your timeline, coordinate with title and escrow, and keep your Prop 19 paperwork on track while we focus on the right home. When you are ready, Request Your Free Home Valuation with Kailani Kimoto.
FAQs
Who qualifies for a Prop 19 transfer in Contra Costa?
- Homeowners who are age 55 or older, severely disabled, or displaced by wildfire or another natural disaster may qualify to transfer their taxable value to a replacement primary residence, subject to county administration.
How many times can I transfer my base value under Prop 19?
- Most age 55 or severely disabled homeowners can transfer up to three times; disaster-related transfers have special rules. Confirm your eligibility and count with the Contra Costa County Assessor.
Does Prop 19 let me move anywhere in California and keep my base value?
- Yes, intercounty transfers are permitted statewide. You file your claim in the county of your replacement home, following local assessor instructions.
What is the timing window for buying and selling under Prop 19?
- A commonly applied rule is up to two years before or up to two years after the sale of your original home. You must also meet county filing deadlines, so verify the current requirements with the Contra Costa Assessor.
How is my new assessed value calculated if I buy a more expensive home?
- The new assessed value is typically your original taxable value plus the difference between the replacement home’s market value and the original home’s market value at transfer.
Do Prop 19 rules apply to vacation or rental homes?
- No. The transfer applies only to your principal residence and the replacement must also be your principal residence.
