California operates under Proposition 13's acquisition-value system, which limits annual increases to the CPI capped at 2% — except on change of ownership or new construction. Appeals are filed with each county's Assessment Appeals Board. Most counties run a regular filing window of July 2 through September 15, but counties that mail value notices to all owners by August 1 use July 2 to November 30. Decline-in-value (Prop 8) appeals are the bread and butter of CA commercial appeal practice, especially for office in 2025-26.
Verify before filing. Statutory deadlines change, and many counties operate on their own schedule inside the state framework. Always confirm the current year's window with the assessor or appeal board for the specific jurisdiction before relying on a date.
State-level deadlines plus major sub-jurisdictions where the schedule diverges from the state default. Where a column says "Varies," confirm the date with the local assessor.
| Month | Type | Event | Date | Details |
|---|---|---|---|---|
| January | RP | Lien date |
January 1 | Statewide lien date — values are set as of January 1 for the upcoming fiscal year (July 1 - June 30). |
| April | BPP | Business Property Statement (Form 571-L) due |
April 1 (filing) / May 7 (penalty date) | BPP filing required for businesses with $100K+ in personal property. 10% penalty after May 7. |
| July | RP | Regular appeal filing window opens |
July 2 | Filing window opens July 2 in all 58 counties. |
| September | RP | Appeal deadline (standard counties) |
September 15 | Filing window closes September 15 in counties that do not mail value notices to all property owners by August 1. |
| November | RP | Appeal deadline (notice counties) LA, Orange, San Francisco, Santa Clara, others |
November 30 | Filing window closes November 30 in counties that mail value notices to all property owners by August 1 (includes Los Angeles County and many others). Verify each county's status. |
| Varies | RP | Supplemental / escape assessment |
60 days from notice | Appeals from supplemental or escape assessment notices must be filed within 60 days of the notice mailing date. |
RP = Real Property · BPP = Business Personal Property · Both = Applies to both
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