Proposition 13 turns 50 in 2028. Its assessment-cap children now run in a dozen states, and Florida wants to go further. The evidence, in full.
In the summer of 2003, Warren Buffett was doing a favor for a friend. Arnold Schwarzenegger was running for governor of California, and Buffett was his economic adviser. A Wall Street Journal reporter asked about property taxes, and Buffett reached for his own tax bills. He owned three houses: a $4 million Laguna Beach home bought in the early 1970s, carrying $2,264 in property tax; a second Laguna Beach home, worth about $2 million and bought in the mid-1990s, carrying $12,002; and a $500,000 house in Omaha, carrying $14,401. The two California homes sat in the same neighborhood, had the same owner, the same ability to pay — and one paid roughly ten times the rate of the other, because of a single variable: when he bought them. "In effect, it makes no sense," he said. He was describing Proposition 13 — and the numbers have never stopped being true.
In June 1978, California voters passed Proposition 13 amid anger over soaring assessments. The measure cut the property tax rate to 1 percent of assessed value, capped annual assessment increases at 2 percent (or inflation, whichever is less), and ordered that a home be reassessed at market value only when it changed hands. A homeowner's bill would be anchored to the year they bought, not the market around them. What supporters understood as protection, and Buffett later called capricious, was the same mechanism.
The economic consequences were immediate and permanent. When a tax benefit attaches to staying put, people stay put. In an NBER working paper, Nada Wasi and Michelle White found that between 1970 and 2000, the average tenure of California homeowners rose by 1.04 years relative to comparable states — a 10 percent increase — and renter tenure rose 0.79 years, a 19 percent increase. The renter finding is the tell: when longtime owners don't sell, younger households get stuck renting longer. A Wharton study by Fernando Ferreira exploited a natural experiment — Propositions 60 and 90, which let homeowners over 55 transfer their low assessment to a new home — and found 55-year-old Californians were about 25 percent more mobile than 54-year-olds. The cap was the lock; the birthday was the key. And an equilibrium model by Ayse Imrohoroglu, Kyle Matoba, and Selale Tuzel estimated that Prop 13 raised California home prices by 18 percent while cutting the probability of moving by 17 percent. The tax break gets capitalized into the price: the seller collects the value of the low tax, and the buyer pays more for the house while losing the benefit.
Other states read the script and adapted it. Florida's voters created the Save Our Homes cap in 1992 — in force since 1995 — limiting annual assessment growth on homestead properties to 3 percent, with full market value returning only at sale. Michigan's Proposal A, approved in 1994, capped taxable-value growth at 5 percent or inflation, whichever is less, resetting on sale. Texas caps homestead assessment growth at 10 percent a year. The Lincoln Institute counts about a dozen states plus Washington, D.C., with some form of parcel-specific assessment limit, and its studies keep finding the same signature distortion: in 2024, two identical townhouses in the same Coconut Grove condo complex in Miami owed wildly different taxes — $4,092 for the unit bought in 2006, $14,693 for the one bought recently, nearly $900 a month more. In Jacksonville, a new buyer of a median-valued home faces an effective rate 64 percent higher than an equally valued home bought in 2010. In Los Angeles, the average homeowner has lived in place 13 years — and pays 39 percent less than a new buyer of the same house.
The caps have never gone unchallenged — they have simply never lost. In 2020, California voters rejected Proposition 15, the "split roll" initiative that would have reassessed commercial property at market value, by a 52–48 margin. On the same ballot, they approved Proposition 19, 51–49, expanding portability — homeowners over 55, the severely disabled, and disaster victims can now carry their low assessment anywhere in California, up to three times — while sharply narrowing the parent-child inheritance exclusion. The message was legible: Californians will not tax the family home at market value, but they will tinker at the edges.
Now the frontier has moved to Florida, where Governor Ron DeSantis spent 2025 pushing not a cap but elimination. The legislature compromised: on June 2, 2026, it passed HJR 1F, which goes to voters as Amendment 3 on November 3, 2026, needing 60 percent to pass. It would raise the homestead exemption to $150,000 of assessed value in 2027 and $250,000 in 2028 for non-school levies, tighten the non-homestead assessment cap from 10 to 5 percent, and direct the legislature to lay the groundwork for eventual elimination. The Institute on Taxation and Economic Policy estimates the measure would cost local governments $13.7 billion in its first two years; state economists put the annual loss at roughly $5 billion in year one, growing toward $12 billion. DeSantis has distanced himself from the final version — it leaves the school portion of the bill, about 40 percent of the total, untouched — and says he'll vote yes but won't campaign for it.
The case for caps is not frivolous. The 1978 revolt happened because annual market-value taxation was genuinely pushing fixed-income seniors out of paid-off homes; a tax you cannot plan for is a tax that can evict you. Defenders also note that revenue hasn't collapsed: California's collections kept growing through turnover, the 2 percent annual creep, new construction, and local parcel taxes. The counterargument to "caps starve cities" is that cities found other revenue — the question is whether the substitutes are better or worse.
The honest accounting is that both sides are describing the same trade. Caps convert a market-based tax into a tenure-based one. They protect the longtime owner and charge the new arrival, subsidize stability and tax mobility, and transfer the benefit from the elderly poor they were built for — who often can't move to use it — to whoever holds a house longest in the hottest markets.
For anyone building property-tax estimates, that is the point. In a capped state, the most valuable variable in the model isn't market value, millage rate, or comps. It's tenure — how long the current owner has sat on the benefit, and how much of it evaporates the day they sell. Prop 13 turns 50 in 2028 and its children are spreading; the data business that prices the lock-in house by house will own the number every buyer, lender, and appraiser in those states needs.
The category-defining name in property tax intelligence — propertytaxestimates.com — is currently available for acquisition by the firm positioned to own this space.
