The Boundary Inside 90210 That Decides Who Pays Measure ULA

A $35 million spec mansion went on the market this month on Donhill Drive, carrying a Beverly Hills mailing address and the famous 90210 zip code. The developer, Ramtin Ray Nosrati, built it in the hills above Sunset, in the section of Los Angeles known informally as Beverly Hills Post Office. If it sells at asking price, the seller owes roughly $1.9 million in Measure ULA transfer tax. An identical estate a few streets away, inside the actual incorporated City of Beverly Hills, would owe none of it.

Same zip code. Same mailing city. Same real estate agent's dream of a listing photo with palm trees and a gate. Completely different tax bill. The line that decides which of those two outcomes applies to a given parcel is not visible from the street, not printed on the listing sheet, and not something most buyers think to ask about until an escrow officer brings it up.

The Line Runs Through the Zip Code, Not Around It

When Beverly Hills incorporated in 1914, its northern border landed roughly a mile north of Sunset Boulevard, with the exception of what later became Trousdale Estates. Everything above that line, stretching up to Mulholland Drive, stayed part of Los Angeles. For decades that hillside land was rural and largely anonymous. In the 1920s the federal government assigned it to the Beverly Hills post office for mail delivery purposes only, and in 1963 the area was folded into the new 90210 zip code alongside the northern part of the actual city.

That postal decision is the reason a buyer today can look at a 90210 listing in Benedict Canyon, Coldwater Canyon, or one of the guard-gated communities like Beverly Park, Mulholland Estates, The Summit, or Beverly Ridge Estates and have no way of knowing, from the address alone, whether the property sits in Beverly Hills or in Los Angeles. Locals call this area Beverly Hills Post Office, or BHPO. It carries the name and the zip code. It does not carry the city limits, the police department, the fire department, or the school district.

It also, since 2023, does not carry an exemption from Los Angeles' Measure ULA.

What Crossing the Line Costs at the Top of the Market

Measure ULA is a City of Los Angeles transfer tax, not a countywide one. Beverly Hills, as an independent incorporated city, sits entirely outside it. The only transfer tax on a Beverly Hills sale is the standard 0.11 percent Los Angeles County documentary transfer tax, regardless of price. A BHPO property a few blocks away, because it falls inside Los Angeles city limits, carries the county tax plus the city's own 0.45 percent base transfer tax plus, above certain thresholds, the ULA surcharge itself.

Those thresholds moved this year. For any transaction closing after June 30, 2026, the Los Angeles Office of Finance set the ULA bands at 4 percent on sales between $5.4 million and just under $10.9 million, and 5.5 percent on anything at or above $10.9 million. Both rates apply to the full sale price, not just the amount above the line.

Run the math on two otherwise identical Westside estates:

The Donhill Drive listing sits at the far end of that scale. At its $35 million ask, the ULA portion alone runs roughly $1.9 million, a bill that exists purely because of which side of an invisible 1914 boundary the parcel happens to fall on.

The Tax Is Shaping Where Money Moves, Not Just How Much It Costs

The dollar figures are one thing. The behavioral shift they've produced is the more interesting story for anyone comparing neighborhoods this year.

Research out of UCLA found that Measure ULA has cut the odds of a Los Angeles property selling above the $5 million threshold by roughly 55 percent since the tax took effect. A separate Cato Institute analysis, cited in recent local reporting on the Donhill Drive listing, put the reduction in transaction volume for eligible high-value properties at around 38 percent. County-wide, sales of $20 million or more fell 28 percent between January 1 and July 31, 2026, compared with the same period the year before.

None of that means demand for Westside luxury real estate disappeared. It means a meaningful share of it rerouted. Capital that would once have gone toward a Bel Air or Brentwood estate inside Los Angeles city limits has increasingly landed instead on tax-exempt ground in Beverly Hills proper. Redfin data for Beverly Hills shows a median sale price of $4.0 million over the three months ending July 2026, up 18.2 percent from the same period a year earlier, with homes now averaging 70 days on market compared with 52 days the prior year. Prices climbing while days on market also climb is not a market cooling. It reads more like a market absorbing buyers who are being more selective about location within a boundary that, for anyone near the $5 million mark, now functions almost like a second layer of pricing.

Why This Isn't a Wait-and-See Situation

Sellers weighing whether to list now or wait for the tax to soften have less room to wait than a lot of the coverage from earlier this year suggested. The Howard Jarvis Taxpayers Association spent much of 2025 and early 2026 gathering signatures for a statewide ballot initiative that would have capped municipal transfer taxes at a fraction of a percent and effectively gutted Measure ULA along with similar taxes in other California cities. That measure qualified for the November 2026 ballot.

It will not appear on it. A last-minute deal in Sacramento, reported by LAist, led the initiative's sponsor to withdraw it shortly before the state's deadline to remove qualified measures, in exchange for state lawmakers advancing Assembly Bill 736. That bill would cap transfer taxes on non-mansion property, apartment buildings, retail, and other commercial types, at 1.5 percent. It leaves the mansion tier exactly where it is: homes over $5.4 million still face the 4 and 5.5 percent rates, untouched by the compromise. AB 736 itself now faces an uncertain path through the legislature.

The practical upshot for anyone pricing a Westside estate this fall is that the boundary math is not a temporary wrinkle to ride out until November. The highest-value tier of the market, the one most likely to be weighing Beverly Hills against BHPO or against Bel Air, got no relief from this year's political fight and has no clear relief coming.

Why the Address on the Escrow Papers Isn't Proof of Anything

The confusion this boundary creates isn't limited to tax bills. In January 2012, when actress Demi Moore needed an ambulance from a home in the area, Beverly Hills and Los Angeles 911 operators spent more than two minutes determining which jurisdiction was actually responsible for responding. If emergency dispatch can lose two minutes to a boundary that residents assume is settled by their own mailing address, a buyer or seller assuming the same thing before signing a purchase agreement is taking on real risk.

The fix is not complicated, but it has to happen before a price gets set or an offer gets written, not during escrow. Verifying whether a specific parcel sits inside the City of Beverly Hills or inside Los Angeles is a matter of checking the parcel's actual municipal jurisdiction, not its zip code or its mailing city. For anyone near the $5.4 million or $10.9 million thresholds, that single check determines whether Measure ULA is part of the transaction at all.

Does a Beverly Hills, CA 90210 mailing address mean a sale is exempt from Measure ULA? No. Exemption follows the parcel's actual city boundary. Homes in Beverly Hills Post Office carry the Beverly Hills name and the 90210 zip while sitting inside Los Angeles city limits, which means they are fully subject to the tax above current thresholds.

Is there any indication Measure ULA will change again soon? Not in the near term. The one statewide effort that could have rolled it back was withdrawn from the November 2026 ballot, and the legislative compromise that replaced it leaves the tax rates on properties over $5.4 million unchanged.

A sale near either threshold is one of the few places in a Westside transaction where a boundary drawn more than a century ago still decides the outcome down to six figures. If you're weighing a purchase or a sale anywhere near that line, whether it's a BHPO estate, a Beverly Hills flats property, or something in between, Renée Avedon can help you confirm exactly which side of it you're on before you price anything.