An address can say "Los Angeles, CA" and sit outside the City of Los Angeles. One that says "San Jose, CA" can sit on county land that San José has never annexed. That surprises a lot of people, because the city name looks official and it's printed on every envelope you get.
The last line of an address is chosen by the Postal Service to get mail delivered. Which city's rules apply to a place is a separate question, and in Los Angeles County and Santa Clara County the two answers disagree often enough that both counties publish warnings about it.
This piece covers what the Postal Service and the two counties say, a three-step check you can run on any address, and what changes when the city on the envelope turns out to be the wrong one. We sell mailbox addresses in Silicon Valley and Los Angeles, so there's a short section near the end about how this applies to ours.
Does the city in my mailing address mean I'm in that city?
It may or may not, and the Postal Service says so in its own fact sheet on ZIP Code boundaries: "ZIP Code assignments are closely linked to factors such as mail volume, delivery area size, geographic location, and topography, but not necessarily to municipal or perceived community boundaries."
The same fact sheet describes a review process for cities that want their own name on addresses. One outcome it lists is "to allow the alternate use of more than one city name in the last line of an address, while retaining the use of the ZIP Code of the Post Office providing delivery." So a single ZIP Code can carry more than one acceptable city name.
USPS Publication 28, the addressing standard, only governs which names are acceptable for mail. It says "It is strongly recommended that addresses use only approved Last Line (city) names as described in the Postal Service City State file currently in effect." Being an approved mailing name tells you the mail will arrive. It says nothing about which city council, tax office, or planning department has authority over the building.
Why is this so common in Los Angeles County?
Because so much of the county isn't inside any city. LA County's planning department puts it plainly: "More than 65 percent of Los Angeles County is unincorporated." The same page says "There are approximately 120 to 125 unincorporated areas, depending on how you define them," and that for the people living there, the Board of Supervisors is their "city council."
The county also names the exact confusion this article is about: "Residents of unincorporated areas can be unsure which jurisdiction they belong to due to their mailing address listing an adjacent city. Use the LA County Jurisdiction Lookup tool to find out if you are in an unincorporated area and if LA County Planning is your planning department."
The other version of the problem involves two incorporated cities. The USPS point about ZIP Codes applies between cities too, so a "Los Angeles" mailing line doesn't by itself place an address inside the City of Los Angeles, and neighboring cities can carry different rates on the California Department of Tax and Fee Administration (CDTFA) table. Culver City's rate differs from the City of Los Angeles's, for example. The county describes its Jurisdiction Lookup as a check for unincorporated areas, so for a mix-up between two cities, CDTFA's rate lookup (step 3 below) is the more direct check.
What about San Jose and Santa Clara?
Santa Clara County's planning department says the same thing in almost the same words. Its page on finding a jurisdiction explains: "Since your mailing address (assigned by the Post Office) may not be the same as your correct municipal jurisdiction, we have provided a method for you to determine which fire agency to contact."
That page is written for fire and code enforcement questions, but the method works for any jurisdiction question. You look up the parcel in the County Assessor's records and read its Tax Rate Area. The county's own wording is that "The information on the Tax Rate Area (TRA) tab can be used to determine which Jurisdiction the property falls in to (TRA format: 017-222)." The first three digits map to a jurisdiction in the county's table.
| First three digits of the TRA | Jurisdiction, per the County's table |
|---|---|
| 017 | City of San Jose |
| 007 | City of Santa Clara |
| 009 | City of Sunnyvale |
| 012 | City of Milpitas |
| 054 to 089 | Unincorporated |
Unincorporated land in Santa Clara County is often surrounded by a city on every side. Santa Clara LAFCO, the county's boundary agency, calls these pockets "islands" and says: "Despite the fact that these islands are completely or substantially surrounded by a city, they remain under the land use authority of the County." LAFCO reports that about 82 islands have been annexed into their cities, and adds: "However, many islands still remain." An address in one of them can carry a San Jose mailing line and still be county land.
How do I check any address in two minutes?
Three official tools cover both regions. Run the address through whichever of the first two applies, then through the third.
- Los Angeles County addresses: the LA County Jurisdiction Lookup. It's on LA County Planning's site, in the area lookup section of planning.lacounty.gov. Enter the street address. The county built it to answer whether an address is in an unincorporated area and whether LA County Planning is its planning department.
- Santa Clara County addresses: the Tax Rate Area on the Assessor's parcel record. Search the property in the Santa Clara County Assessor's records and open the Tax Rate Area information. Compare the first three digits with the table above. The county page we read dates from mid-2025, and the Assessor's search tool may have been renamed since, so if the steps don't match what you see, look for the property search on the Assessor's site. For a suite in an office building, look up the building's parcel. The city is the same for every suite in it.
- Any California address: CDTFA's rate lookup at maps.cdtfa.ca.gov. The California Department of Tax and Fee Administration links it as "Find a Sales and Use Tax Rate by Address." It returns the sales and use tax rate for that exact location, and it works in both counties.
If a result looks off, CDTFA also notes that "Some cities have developed lists of addresses to help retailers and consumers in identifying addresses located within their city." The city's own finance or planning office is the place to ask.
Which sales tax rate applies if my mailing city is different?
The rate follows where the location actually is. CDTFA's city and county rate table carries this note: "Please note, unincorporated cities and communities are not listed below. If the location you are searching for is not within the boundaries of an incorporated city, the county unincorporated area rate or county rate for that location will apply."
In practice, rates a few miles apart can differ. On CDTFA's current table, the City of Los Angeles and Culver City carry different rates, and so do San Jose and Santa Clara. We aren't printing the numbers here, because several of them change on October 1, 2026.
CDTFA's Special Notice L-1037, "New Sales and Use Tax Rates Effective October 1, 2026," lists new rates for places that include the County of Los Angeles, the City of Burbank, and the City of Culver City. The notice says "These rate changes only apply within the indicated city or county limits," which makes the same point again: the boundary decides the rate. It also tells you where to check: "Select Find a Sales and Use Tax Rate by Address under the Current Tax Rates section, enter the address, and select Search. The new rates will be available to search beginning October 1, 2026." CDTFA's rate table page warns that "These rates may be outdated," so the address lookup is the one to trust on any given day.
Does city business tax follow the mailing address?
The rules we read attach city business tax to where business activity happens. The City of Los Angeles Office of Finance says: "All individuals or entities conducting business activities within the City of Los Angeles are required to apply for and obtain a Business Tax Registration Certificate with the City of Los Angeles, Office of Finance." Its tax information booklet ties that to the municipal code: "Anyone engaging in business activity within the City of Los Angeles, as defined in the Los Angeles Municipal Code (LAMC) Section 21.00(i), must register for a Business Tax Registration Certificate and is subject to business tax pursuant to LAMC Section 21."
The LA registration also asks for two addresses separately: "The exact business address and primary mailing address for your business location if different from the business location." A "Los Angeles, CA" mailing line doesn't settle whether you're doing business within the City of Los Angeles. The business address field asks where the business is located.
The City of Santa Clara reaches past its own addresses in the same way. Its business license page says: "Businesses located outside of the City but conducting business activity within city limits are also required to have a Santa Clara business license." San José runs its own business tax, and both cities are covered in our San José and Santa Clara DBA and business tax guide. The Los Angeles side, including which address goes in each BTRC field, is in our Los Angeles DBA and business tax guide. We haven't checked whether every city in LA County levies its own business tax, so if your check lands you in another city, look up that city's finance department directly.
Which county do I file my DBA in?
A fictitious business name statement is filed by county, so the question here is which county the principal place of business is in. Business and Professions Code section 17915 says the statement "shall be filed with the clerk of the county in which the registrant has his or her principal place of business in this state or, if the registrant has no place of business in this state, with the Clerk of Sacramento County." Section 17913 says the form should give "the street address, and county, of the registrant's principal place of business in this state."
That makes a mix-up between Los Angeles and Culver City harmless for the DBA itself, since both are in LA County. A county line is what changes the filing office. The statute text we read doesn't say whether a mailbox address can count as a principal place of business, so we won't claim it does. Our DBA guide covers the filing basics, and our guide to the principal place of business explains what that phrase usually means on forms.
Where a mailbox address helps, and where it doesn't
Auteur is in pre-launch, and orders are open in Silicon Valley and Los Angeles. We don't say here which city or county our addresses are in, because the exact street address is assigned the day each city opens. When we email you your address, run it through the same three checks above, and you'll have the answer from the county and the state directly.
A mailbox address receives mail, and any city name on it is fine for that. It doesn't move where you actually work. City business tax follows where business activity happens, and the sales tax rate follows the jurisdiction of the location, so if you work from a home in Pasadena, the rules for that home still apply whatever address you print on your letterhead.
The Virtual Mailing Address is for personal mail, in individual names only. The Virtual Business Address also receives mail in a business or trade name. Both photograph the envelope of every piece, and we open and scan only when you ask, for one flat fee per piece. USPS Form 1583 is required before any provider can receive mail for you. Pricing comes by email with the next steps. If you want to get your address in Silicon Valley or in Los Angeles, ordering is free, there's no card, and nothing is charged.
FAQ
My address says Los Angeles, CA. Am I in the City of Los Angeles?
You may be, but the mailing line can't tell you. USPS says ZIP Codes don't necessarily follow municipal boundaries, and LA County says mailing addresses in unincorporated areas can list an adjacent city. Enter the address in the LA County Jurisdiction Lookup to see whether it's in an unincorporated area, and run it through CDTFA's address lookup as well.
How do I tell if a Santa Clara County address is unincorporated?
Look up the parcel in the County Assessor's records and read the Tax Rate Area. Under the county's table, first three digits from 054 to 089 mean unincorporated, 017 means the City of San Jose, and 007 means the City of Santa Clara. CDTFA's address lookup at maps.cdtfa.ca.gov is a useful second check.
Does my sales tax rate change if my mailing city is wrong?
The rate depends on the location's actual jurisdiction, and CDTFA says locations outside an incorporated city take the county rate. If your mailing city and your real jurisdiction differ, the real one decides. Several LA-area rates change on October 1, 2026, so use CDTFA's address lookup for the current figure.
Do I owe Los Angeles business tax because my address says Los Angeles?
The City of Los Angeles ties its business tax to "business activities within the City of Los Angeles." Whether you owe it depends on where your business activity happens, and the mailing line on your address doesn't decide that by itself.
Which county do I file a DBA in if my address is near a county line?
Business and Professions Code section 17915 points to the clerk of the county where your principal place of business is, or Sacramento County if you have no place of business in California. Use the county the real location is in. If you aren't sure which side of the line it's on, ask that county's assessor or clerk.
Bottom line
The Postal Service picks the city name on an address to get mail delivered, and it says those names don't necessarily match city limits. The gap is common in Los Angeles County, where more than 65 percent of the land is unincorporated, and in Santa Clara County, with its county islands inside San José and other cities. Before you register for a city business tax, set a sales tax rate, or file a DBA, run the address through the county's own check and CDTFA's lookup, and go by what they say.
