Guide · sources read Nov 9, 2026
How to read a California parcel number
California's Board of Equalization guidance for assessors says a parcel number has three parts: the assessor's map book number, the page (or block) in that book, and the parcel's number on that page.1 Each county prints it its own way (two below).23
Also called the APN (assessor's parcel number).
County by county
Los Angeles County
Los Angeles County calls it the AIN (assessor's identification number): ten digits.2
Example: 2058-004-042. On Groundwork: 2058-004-0423.
| 2058-004-042 | What it means |
|---|---|
| 2058 | map book |
| 004 | page |
| 042 | parcel |
Read from the county's own layout2.
San Diego County
San Diego County's APN corresponds to a location on a page in a book of maps kept by the assessor.4 Groundwork prints it as 498-260-39-00.3
Example: 498-260-39-00. On Groundwork: 498-260-39-003.
Look up a California parcel number
Type the number the way the county prints it. A county not shown here may lay its number out differently; its assessor's site has the layout.
Questions
What is a parcel number in California?
California's Board of Equalization guidance for assessors says a parcel number has three parts: the assessor's map book number, the page (or block) in that book, and the parcel's number on that page. Each county prints it its own way (two below).
How do I look up a California parcel number on Groundwork?
Type it in the map search the way the county prints it. Example from Los Angeles County: 2058-004-042. Groundwork shows it as Parcel 2058-004-042.
Sources
- California State Board of Equalization: Assessors' Handbook Section 215, Assessment Mapping (Parcel Number). Read Nov 9, 2026.
- Los Angeles County Treasurer and Tax Collector: Supplemental Secured Property Tax Bill (bill guide). Read Nov 9, 2026.
- Groundwork map search: each example on this page was searched and returned that parcel first. Checked Nov 9, 2026.
- San Diego County Assessor/Recorder/County Clerk: Mapping Services. Read Nov 9, 2026.