How does the Prop 19 tax base transfer for 55+ work in California?

Who can move their tax base, and how many times

In California, your property tax is based on your home's taxable value, not its market value. If you bought in 1994, your taxable value may be a fraction of what the house would sell for today. Selling and buying again normally resets that number to the new price. For a lot of longtime owners, that reset is the main reason they never move. They are not attached to the house. They are attached to the tax bill.

Proposition 19 gives three groups a way out. According to the State Board of Equalization (BOE), you can transfer your base year value to a replacement home if, on the date you sell your original home, you are:

• 55 or older. If you are married, only one spouse has to be 55.
• Severely and permanently disabled.
• A victim of a wildfire or natural disaster declared by the Governor, where the original home was substantially damaged. The statute defines that as damage of more than 50 percent of the land's or the improvements' value.

The original home has to be your principal residence, not the cabin in Big Bear. The replacement can be in any California county. Owners 55+ and disabled owners can do this up to three times, even if they used the older Propositions 60 or 90 before. Revenue and Taxation Code section 69.6 says that three-transfer limit does not apply to wildfire and natural disaster victims. Homes owned by a corporation or other legal entity do not qualify.

The two-year window and the 100, 105 and 110 percent rule

You have to buy or build the replacement within two years of selling the original. That window runs both ways, so you can buy first or sell first. Buy-first gives you less room on price, though.

The BOE compares the replacement's market value to the original's market value, with a cushion that grows the longer you wait:

One small surprise from the BOE's fact sheet: you must be 55 when the original sells, but you can be younger when you buy the replacement. A 54-year-old can buy first, have a birthday, then sell. Happy birthday, here is a tax break.

What happens if the new home costs more

Under the old rules, buying up usually killed the deal. Under Prop 19, buying up just costs you part of the savings. The BOE says any value above the limit gets added to the taxable value you carry over.

The BOE's own example: an original home worth $400,000 with a $100,000 base year value, and a $600,000 replacement bought in the first year. The limit is 105% of $400,000, or $420,000. The extra $180,000 is added, so the new taxable value is $280,000 instead of $600,000.

Now a hypothetical with Bay Area numbers. Say you sell a San Jose home for $1,800,000. Its factored base year value, the taxable value the assessor carries today, is $420,000.

• Buy smaller. You buy in Elk Grove for $950,000 in year one. That is under the limit, so you keep $420,000 as your taxable value.
• Buy bigger. You buy in Walnut Creek for $2,100,000 in year one. The limit is 105% of $1,800,000, or $1,890,000. The extra $210,000 is added, for a new taxable value of $630,000 instead of $2,100,000.

At California's 1% base rate, before local bonds and assessments, that second move carries a base tax of about $6,300 a year instead of about $21,000. That is a lot of grandkid plane tickets.

Why the sale price and an appraisal matter to the math

Look at what drives every number above: the market value of the home you sold and the market value of the home you bought. Those two figures set the limit and the overage.

Section 69.6 measures the original home's value as a new base year value, as if the assessor reassessed it at the sale. In a normal open-market deal, Revenue and Taxation Code section 110 presumes the purchase price is the value. That is a legal starting point, and the presumption can be rebutted. When a sale was not a normal deal, someone has to show the real number. Cases where I see that matter:

• The original sold to a friend or relative at a discount. A soft price does not make a good benchmark, because the limit comes from market value.
• The original was damaged by fire or disaster. The statute measures it at its value right before the damage, which calls for a retrospective appraisal as of that date.
• You are planning before you list. Your budget for the next house depends on what this one will bring. A guess from a neighbor at the mailbox is not a budget.
• You add on after buying. The BOE says new construction finished on the replacement within two years of the sale can be included in the transfer, up to the original home's market value.

The contract price does not set market value in my world. For property tax, the law starts with it. Knowing both is how you avoid surprises from the assessor.

Mistakes that cost people the transfer

• Forgetting to file. Escrow does not file this for you. The BOE says you file with the assessor in the county where the replacement is, after both deals close and you live there.
• Missing the deadline. The claim is due within three years of buying or finishing the replacement. The BOE says a late claim still works, but only going forward from the year you file. Back years stay lost.
• Waiting too long to buy. The day after the two-year mark is one day too late. Mark the date before the moving truck shows up.
• Giving the old house to a child. The BOE says you cannot use this transfer if the original home goes to a child who claims the parent-child exclusion. That is a different Prop 19 rule, covered in our post on inherited homes.
• Buying with an LLC. Entity-owned property does not qualify. Talk to your attorney before you title anything creatively.

What to do before you sell

1. Get your factored base year value from your property tax bill or the county assessor.
2. Know what your home will sell for. A pre-listing appraisal gives you a market value to plan from, and a solid estimate of your 100, 105 or 110 percent ceiling.
3. Pick your order. Buying first locks you at 100%. Selling first gives you up to 110% but you need a place to live.
4. Put the two-year date on the calendar the day the sale closes.
5. File the right form with the replacement county's assessor: BOE-19-B for 55+, BOE-19-D with the BOE-19-DC certificate for severe disability, or BOE-19-V for wildfire and disaster victims.
6. Talk to your CPA or attorney if the home is in a trust, owned with others, or tied to a divorce.

If you are planning a move anywhere in the state, I work as a California appraiser on pre-listing and retrospective values.