In January 2012, dispatchers had to sort out something a Beverly Hills mailing address doesn't actually settle before they could send help to actress Demi Moore's home. The address said Beverly Hills, CA 90210. The parcel sat outside the Beverly Hills city limits, in the Los Angeles hillside neighborhood most agents call BHPO. Two minutes went by while Beverly Hills and Los Angeles 911 operators worked out whose jurisdiction the call belonged to.
That confusion isn't a historical footnote. It's the same line that now decides whether a seller in the 90210 zip code owes a six-figure tax at closing or pays nothing at all.
One Zip Code, Two Cities
Beverly Hills Post Office, or BHPO, is the informal name for the hillside stretch running from a few blocks north of Sunset Boulevard up to Mulholland Drive, tucked between Benedict Canyon and Coldwater Canyon. It carries the Beverly Hills name because the USPS routes its mail through the Beverly Hills post office, and it shares the 90210 zip code with the actual City of Beverly Hills. But BHPO is a neighborhood inside the City of Los Angeles. Homes there get LAPD and LAFD instead of Beverly Hills Police and Fire, LAUSD school assignments instead of Beverly Hills Unified, and, as of this year, something with a much sharper price tag: full exposure to Los Angeles's Measure ULA transfer tax.
The gated communities inside this stretch have real names buyers recognize: Beverly Park, The Summit, Mulholland Estates, Beverly Ridge Estates, Oak Pass. Cross south into the actual City of Beverly Hills and you're in the Flats, Trousdale Estates, or Gateway, an independent municipality that has never been subject to Measure ULA at all.
The Tax That Only Half the Zip Code Pays
Measure ULA, the tax nicknamed the "mansion tax" when Los Angeles voters approved it in 2022, adds a transfer tax on top of the standard documentary transfer tax whenever a property inside city limits sells above a set price. The thresholds adjust every July 1 based on the Chained Consumer Price Index, and for any closing after June 30, 2026, the current numbers are $5,400,000 and $10,900,000, according to the Los Angeles Office of Finance.
| Sale price | ULA rate | ULA tax owed |
|---|---|---|
| $5,400,000 | 4% | $216,000 |
| $10,900,000 | 5.5% | $599,500 |
The tax applies to the entire sale price, not just the amount above the line, there's no primary residence exemption, and by default the seller pays it at deed recordation. A BHPO listing that closes at $5.4 million owes that full $216,000. A home three miles south in the Flats, at the identical price, owes nothing to ULA at all, because Beverly Hills runs its own transfer tax system and Measure ULA has no authority inside city limits.
The Cliff Effect Changes How Agents Price a Listing
Because the tax kicks in as a hard threshold rather than a gradual marginal rate, a seller can lose more by crossing the line by a few thousand dollars than they'd gain by pricing above it. A BHPO home valued near $5.4 million nets more to the seller listed at $5,395,000 than it would at $5.5 million once the tax is subtracted. That's why threshold pricing, listing deliberately just under $5.4 million or $10.9 million, has become a standard tool for agents working the BHPO side of the boundary.
Luxury agent John Iglar has argued the structure of the tax itself is part of the problem for sellers, since it falls entirely on the seller rather than the buyer:
"In L.A., sellers pay the mansion tax. In New York, buyers pay."
That distinction matters more in BHPO than almost anywhere else in the county, because BHPO sellers are often long-tenured owners with substantial paper equity and comparatively modest cash liquidity, exactly the profile least able to absorb a $200,000 to $600,000 hit at closing without adjusting how they price and time the sale.
Where the Capital Has Actually Moved
The boundary hasn't just changed how individual listings get priced. It's changed where money flows across the entire west side. Transaction volume above $5 million in Los Angeles City neighborhoods like Bel Air, Holmby Hills, and Brentwood has dropped roughly 38 percent since the tax took effect in April 2023, and developers have largely stopped building spec mansions inside city limits altogether. Capital that would have gone into those LA City neighborhoods has migrated toward the tax-exempt side of the boundary, into Beverly Hills proper.
That migration shows up in how Beverly Hills trades today. Roughly 65 to 70 percent of single-family sales in the city close entirely in cash, climbing to 85 to 90 percent in the $10 million-plus tier, a level of liquidity that mostly detaches the top of the market from mortgage rate conditions. At the very top end, close to 40 to 50 percent of transactions above $15 million happen entirely off-market through pocket listings and private agent networks, letting sellers and buyers work around the exposure that comes with a public listing near a threshold.
Why "the Beverly Hills Median Price" Keeps Contradicting Itself
If you've priced out Beverly Hills online this year, you've probably noticed the median sale price quoted depends almost entirely on where you look. Figures published in 2026 have ranged from around $3.2 million to $7.8 million for what's described as the same market. That's not a rounding error. It's the BHPO boundary showing up in the data.
BHPO's own median sale price this year has run in the $3.0 million to $3.2 million range, the widest price disparity of any pocket in the zip code, with individual sales stretching from under $2 million to more than $35 million depending on lot size and canyon position. Beverly Hills proper, the Flats and Trousdale Estates, has traded in a much higher and narrower band, with quarterly medians reported well above $6 million and even topping $7.8 million in the first quarter of 2026. A widely quoted figure that lands close to $3.2 million for "Beverly Hills" is very likely capturing BHPO's canyon sales alongside, or instead of, the incorporated city. A figure closer to $6 million or above is more likely counting only sales inside true city limits.
The price-per-square-foot gap tells the same story from a different angle. Comparable finishes and lot sizes routinely price more than $400 per square foot higher inside actual Beverly Hills city limits than in BHPO, a spread large enough that it can't be explained by staging or condition alone. Buyers in BHPO are trading tax-exempt status and a shorter commute for more land and more square footage per dollar. Buyers inside the city limits are paying a premium for the municipal boundary itself.
A Line That Has Flipped Before
The BHPO boundary hasn't always favored the same side. Before California's Proposition 13 took effect in 1978, BHPO carried higher property taxes than the incorporated city, and buyers accepted that trade-off for more land at a lower purchase price. Prop 13 equalized the base rate and erased that disadvantage almost overnight. Measure ULA is doing something similar in reverse nearly fifty years later: a single piece of tax policy reshaping which side of an old, largely invisible line buyers and sellers want to be on.
What This Means If You're Buying or Selling Near the Line
A 90210 mailing address is not proof of anything beyond where the mail gets sorted. Before you compare a listing's price to a neighbor's, or assume a number quoted online applies to the property you're actually looking at, confirm which municipality holds jurisdiction over that specific parcel. The county assessor's parcel viewer and a preliminary title report will show it plainly, and any agent working this market regularly should be able to pull both before you write an offer or set a list price.
A few questions worth asking directly:
- Is this specific address inside the incorporated City of Beverly Hills, or in the BHPO section of the City of Los Angeles?
- If it's in BHPO, does the current list price sit close enough to $5.4 million or $10.9 million that a small pricing adjustment could avoid the tax entirely?
- Are the comps being used to justify a price pulled from the same jurisdiction, or blended across both sides of the boundary?
Frequently Asked Questions
Does every home with a 90210 zip code owe Measure ULA? No. The tax only applies inside the incorporated City of Los Angeles. Homes in the actual City of Beverly Hills, including those with a 90210 address, are exempt regardless of price.
Who pays Measure ULA, the buyer or the seller? The seller, by default, with no exemption for a primary residence. The obligation can be negotiated in a purchase contract, but absent that negotiation it falls on the seller at the time the deed is recorded.
How do I find out which side of the line a specific address falls on? Check the property's parcel record with the county assessor or request a preliminary title report before you list or make an offer. A mailing address or zip code alone won't tell you.
Pricing near a tax cliff, or comparing two homes that look identical but sit on opposite sides of a city line, is exactly the kind of decision that rewards someone who has already run these numbers before. Denise Marks Group works both sides of this boundary regularly and can walk you through what it actually means for your specific address, whether you're pricing a sale or sizing up a purchase. Request your free home valuation to start with the numbers that apply to your property, not the zip code average.
