Proposition 19 Cost Calculator

If you have owned your California home for a long time, your property tax bill is probably one of the best deals you have. Prop 13 locked in your assessed value years ago, and it has only crept up by about 2% a year since. The fear I hear from almost every longtime homeowner I work with in Silicon Valley is simple: "If I sell and buy something smaller, won't my property taxes triple?" For many people 55 and older, the answer under Proposition 19 is no. This free Prop 19 calculator shows you, in about a minute, what your property taxes could look like if you move, and what your kids could expect to pay if they inherit the family home.

I built this tool because I got tired of watching people make a housing decision, or avoid one entirely, based on a rumor about property taxes. Plug in your numbers below, then keep reading for a plain English explanation of how Prop 19 works, a few real world examples from the Santa Clara County market, and the deadlines that trip people up.

California Prop 19 Calculator

Enter your current assessed value (you can find it on your property tax bill or on the Santa Clara County Assessor's website), what you expect to sell for, and the price of the home you are thinking about buying. The calculator estimates your new assessed value and your approximate annual property tax, and compares it to what you would pay without Prop 19.

What Is Proposition 19?

California voters passed Proposition 19 in November 2020, and it changed two big things about how property taxes work for homeowners. The first change was good news for older adults who want to move. Homeowners 55 and older, severely disabled homeowners, and victims of wildfires or natural disasters can now take their low Prop 13 tax base with them when they buy a replacement home anywhere in California. Before Prop 19, that kind of transfer was limited to a single move and only to a handful of counties that opted in, so a lot of people stayed stuck.

The second change was tougher on families. Prop 19 narrowed the old parent to child exclusion, which used to let children inherit a home, and up to $1 million of other property, at the parents' assessed value regardless of how the kids used it. Now the inherited home has to become the child's primary residence to keep any of that tax break, and even then there is a cap on how much value comes along. Rentals and vacation homes passed to children get reassessed to market value.

Prop 19 for Homeowners 55 and Older: Transferring Your Tax Base

This is the part of Prop 19 that opens up real options for people who are ready to downsize, move closer to family, or get into a single level home. Here is how the base year value transfer works.

• Who qualifies: At least one owner must be 55 or older on the date the original home is sold. Severely disabled homeowners of any age and victims of a governor declared wildfire or natural disaster also qualify.
• Where you can move: Anywhere in California, in any county. You are not limited to staying in Santa Clara County.
• How many times: Homeowners 55 and older and severely disabled homeowners can use it up to three times in their lifetime.
• Timing: You must buy or build your replacement home within two years of selling your original home, either before or after the sale.
• Primary residence: Both homes must be your principal residence and eligible for the homeowners' exemption.
• Filing: You file a claim with the assessor in the county where the replacement home is located, using BOE-19-B for age 55 and over.

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The "Equal or Lesser Value" Test

Your full tax base transfers if the replacement home is of equal or lesser value than the home you sold. What counts as "equal or lesser" depends on when you buy. If you buy the replacement before you sell, it can be up to 100% of the sale price of your original home. If you buy within the first year after selling, it can be up to 105%. If you buy in the second year, up to 110%.

If the new home costs more than that, you still get a benefit, which is where Prop 19 really differs from the old rules. The difference between the two market values is simply added to your existing tax base. That means buying a more expensive home, which was never allowed under the old Prop 60 and Prop 90, is now a realistic choice for a lot of people.

Example: Downsizing in Los Gatos

Say you bought your Los Gatos home in 1992 and your assessed value today is about $450,000. You sell it for $2,800,000 and buy a single level home in Campbell for $2,200,000. Because the new home is less than what you sold for, your $450,000 tax base comes with you. At an effective tax rate of roughly 1.2%, which is typical in parts of Santa Clara County once local bonds are added, your annual property tax would be around $5,400. Without Prop 19, you would be assessed at the $2,200,000 purchase price and pay about $26,400 a year. That is a savings of roughly $21,000 every single year.

Example: Moving to a More Expensive Home

Now say the same seller buys a $3,000,000 home eight months after closing on the $2,800,000 sale. The 105% limit for a first year purchase is $2,940,000, so the new home is over the line. The $200,000 difference between the two prices gets added to the $450,000 base, giving a new assessed value of about $650,000. The estimated tax would be around $7,800 a year instead of roughly $36,000 at full market value.

Prop 19 and Inheriting a Family Home

This is the section I spend the most time on with adult children, because the rules are unforgiving if you miss a deadline. Under Prop 19, when a parent transfers a family home to a child (or to a grandchild whose parents have passed away), the home can keep some or all of the parent's tax base only if these conditions are met:

• The home was the parent's principal residence.
• The child moves in and makes it their own principal residence within one year of the transfer.
• The child files for the homeowners' exemption within one year.
• A claim for reassessment exclusion (BOE-19-P) is filed with the county assessor, generally within three years of the transfer.

Even when all of that happens, there is a cap. The child can keep the parent's assessed value plus an exclusion amount that is adjusted for inflation every two years. From February 16, 2025 through February 15, 2027, that amount is $1,044,586. If the home's market value is more than the parent's assessed value plus $1,044,586, the difference gets added to the tax base.

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Example: Inheriting a Home in San Jose

Mom's home in Willow Glen has an assessed value of $400,000 and is worth $2,500,000 today. Her son inherits it and moves in within the year. The exclusion limit is $400,000 plus $1,044,586, or $1,444,586. The home is worth $1,055,414 more than that, so his new assessed value would be about $1,455,414. His estimated tax would be around $17,500 a year, compared to roughly $30,000 if the home were reassessed at full market value and about $4,800 on mom's bill. If he decides to rent the house out or keep it as a second home instead of living there, it gets reassessed at the full $2,500,000.

For families in the Bay Area, where so many longtime homes are worth well over the exclusion cap, it is worth sitting down with an estate planning attorney before anything is transferred. The decisions you make about a trust, a sale during your lifetime, or who will live in the home can make a difference of tens of thousands of dollars a year.

Prop 19 Deadlines and Forms at a Glance

• Replacement home purchase (55+): Within two years of selling your original home.
• Base year value transfer claim (55+): BOE-19-B, filed with the assessor in the county of the replacement home, generally within three years of buying the replacement.
• Child moves into inherited home: Within one year of the transfer.
• Homeowners' exemption on inherited home: Within one year of the transfer.
• Parent to child exclusion claim: BOE-19-P, generally within three years of the transfer or before the property is sold to someone else.

Frequently Asked Questions About Prop 19

Can I use Prop 19 to move to another county?

Yes. One of the biggest changes under Prop 19 is that the base year value transfer works in every California county. You can sell in Santa Clara County and buy in Santa Cruz, Sacramento, or San Diego County and still bring your tax base with you.

Can I buy a more expensive home and still save?

Yes. If the replacement costs more than the "equal or lesser value" limit, the difference in price is added to your current assessed value. You won't keep your entire base, but you will usually pay far less than you would at full market value.

Do both spouses have to be 55?

No. Only one owner needs to be 55 or older on the date the original home is sold, and they need to be an owner of both the original and replacement homes.

How many times can I use Prop 19?

Homeowners who qualify based on age or severe disability can transfer their base year value up to three times. The old Prop 60 and Prop 90 rules only allowed a single transfer.

What happens if my kids inherit my house and don't live in it?

The home is reassessed to its current market value as of the date of transfer. For a lot of Silicon Valley homes, that can mean a property tax bill that is five or six times what the parents were paying.

What is the Prop 19 exclusion amount for 2026?

The family home exclusion amount is $1,044,586 for transfers from February 16, 2025 through February 15, 2027. The State Board of Equalization adjusts it every two years, so the next change is scheduled for February 16, 2027.

Where do I find my current assessed value?

Look at your most recent property tax bill or search your address on the Santa Clara County Assessor's website. Use the assessed value, not the market value or the Zestimate, when you run the calculator above.

Thinking About Your Next Move? Let's Talk It Through.

I have spent more than 23 years helping longtime Silicon Valley homeowners and their families figure out what comes next, and property taxes are almost always part of that conversation. As a Seasoned Living Strategist with the SRES and CSA designations, I can help you run the numbers on selling, compare replacement homes, time your purchase around the Prop 19 deadlines, and coordinate with your CPA and estate attorney so nothing falls through the cracks.

If this calculator raised more questions than it answered, that is a good sign you are asking the right ones. Reach out and we can walk through your situation together, with no pressure and no obligation.

Disclaimer: This page is for general informational purposes and is not tax or legal advice. Property tax rules, exclusion amounts, and filing deadlines can change, and your county assessor makes the final determination. Please consult a qualified tax professional or attorney about your specific situation.

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