Reserve Tax AI
California · Nov 30, 2026 · 47 days left

California property tax appeals. Nov 30 is the line.

Appeals close November 30, 2026 in Los Angeles, Orange, San Diego and 44 other counties. If you bought or built since 2019, you likely have a case. We screen every parcel and file the ones worth filing.

Screen my California portfolio How Prop 13 works for commercial →
47
counties open through Nov 30
2%
max annual increase under Prop 13
Jan 1
lien date your value is tested against
18%
of the savings, only when we win
2026 regular filing period · by county

One state, two deadlines.

Most of the state, including every large Southern California county, is open through Monday, November 30, 2026. Early-notice counties closed September 15.

Open through Nov 30, 2026 47 counties

November 30 counties

Received or postmarked by November 30. Send your parcel list as early as you can.

Los AngelesOrangeSan DiegoRiversideSan BernardinoSacramentoSan MateoContra CostaFresnoKernSanta BarbaraSonomaMarinNapaMontereySan JoaquinStanislausSolanoTulareSanta Cruz+ 27 more
Closed Sept 15, 2026 Early-notice counties

September 15 counties

Closed for 2026. Supplemental and escape assessments still have 60 days from the notice. Next window opens July 2, 2027.

AlamedaSan FranciscoSanta ClaraVenturaPlacerSan Luis ObispoKingsInyoMonoAlpineSierra

Source: California State Board of Equalization, Letter to Assessors 2026/023, 2026 assessment appeals filing periods. Confirm your parcel's county and deadline before relying on it.

Proposition 13 · commercial property

How Prop 13 works when the property is commercial.

Commercial property is assessed on its purchase price, not today’s market value. The question is simple: is it worth less on January 1 than the number Prop 13 carried forward? For buildings bought in 2019 to 2022, often yes.

01 · Base-year value

Set at purchase

A sale or new construction sets the base-year value, normally the price paid.

02 · Factored base-year value

Up 2% a year, max

It rises with inflation, capped at 2% a year. That is the ceiling on your assessment.

03 · Prop 8 decline in value

Lower of the two

If market value on January 1 is lower than the ceiling, you are owed the lower number. That is the appeal.

Insights · 7 min readProp 13, Prop 8, Prop 19 and Prop 15, explained, with a worked office example Read the guide
Who actually has a case

Screen by purchase date first.

Anything bought or built since 2019 goes to the model. Older holdings are usually far below market and come off the list.

Strong

Office bought 2018 to 2022

Peak prices, then vacancy and rising cap rates.

Strong

Retail, hotels and multifamily bought 2020 to 2022

Bought at low cap rates where income never caught up to the price.

Strong

New construction finished 2022 to 2025

Assessed near cost, even when income does not support it.

Check

Restaurant and net-lease real estate

Recent purchases and remodels. Burger King franchisees get the program rate statewide.

Rarely

Held since before 2015

Usually assessed far below market. Nothing to appeal.

How Reserve runs California

From parcel list to filed application in under three weeks.

Send the parcel list. We come back with the parcels worth filing, the projected savings on each, and one authorization to sign.

Send my parcel list
The California timeline
1

Days 1 to 3: pull the record. Base year, factored base and roll value for every parcel, from the assessor.

2

Days 3 to 7: model January 1 value. The AVM flags parcels worth less than their factored base.

3

Days 7 to 14: authorize. One agent authorization per owner of record.

4

Before Nov 30: file. Form BOE-305-AH with each county’s Assessment Appeals Board.

5

After filing: settle or hear. Many settle with the assessor before hearing. Refunds are paid with interest.

Filed and argued by Reserve Tax Group under written owner authorization.

18% of the savings, only on wins. Traditional consultants charge 25% to 35%. Reserve vs. traditional consultants →
California FAQ

Questions California owners ask.

The regular filing period runs July 2 through November 30, 2026 in 47 counties, including Los Angeles, Orange, San Diego, Riverside, San Bernardino, Sacramento, San Mateo, Contra Costa, Fresno and Kern. In counties that mail notices to all owners by August 1 (Alameda, San Francisco, Santa Clara, Ventura, Placer, San Luis Obispo and a handful of small counties) the period closed September 15. Applications must be received or postmarked by the deadline.
Yes. Prop 13 covers all real property in California. A commercial parcel gets a base-year value at purchase or new construction, normally the price paid, and that value rises no more than 2% a year. The 2020 split-roll measure (Prop 15) that would have moved commercial property to market-value assessment failed, so commercial property is still under Prop 13.
Prop 8 requires the assessor to enroll the lower of factored base-year value or market value on the January 1 lien date. If your property is worth less on January 1, 2026 than its factored base-year value, you are entitled to the lower number for the 2026-27 tax year. The reduction is temporary: the assessor reviews it each year and restores value as the market recovers, up to the factored base.
Mostly properties purchased or reassessed in roughly the last five to seven years. Office bought before 2023 is the clearest case, followed by retail, multifamily and hotels bought at peak pricing, and new construction assessed near cost. Properties held since before 2015 are usually assessed far below market and have nothing to appeal.
A decline-in-value appeal argues market value on January 1 is below the factored base; it covers one tax year and is temporary. A base-year value appeal challenges the base-year value itself, for example because the price included business value, furniture and equipment, or above-market leases, or was not a market price. It must be filed within four years of the year the base was first enrolled, and a win is permanent and factored forward.
Filing does not reset your base year. The board can in principle find a value higher than the roll value in a decline-in-value case, but it is bound by the factored base-year value as the ceiling, so a long-held property cannot be pushed to market value by appealing. Reserve only files where the model shows a credible gap, which keeps that risk theoretical.
File an Assessment Appeal Application (form BOE-305-AH) with the clerk of the county Assessment Appeals Board, stating your opinion of value and the appeal type. An authorized agent can sign and appear with the owner's written authorization. Los Angeles County also requires tax agents who appear before its board to register under the county's Tax Agent Registration Program. The board has two years to decide; successful refunds are paid with interest.
18% of the savings, only when we win. No reduction, no fee, and the Reserve Intelligence platform is included. The traditional consulting model is typically 25% to 35% contingency on an engagement reviewed site by site. We publish our rate; ask any firm to do the same, and ask how many of your parcels they will actually model before filing.
You lose the regular appeal for the 2026-27 tax year and the next regular period opens July 2, 2027. Supplemental and escape assessments carry their own 60-day windows from the notice date, and some assessors accept informal decline-in-value review requests outside the formal period at their discretion. None of those is a substitute for filing on time.
California · closes Nov 30 · 47 days

Screen the portfolio before the window closes.

Send the parcel list or the addresses. You get the parcels worth filing and the projected reduction on each. Free, no obligation to file.

Received. We’ll come back with your California screen and next steps.
California screen · No commitment

Which of my parcels are worth filing?

Tell us about the portfolio. We’ll follow up within one business day with what we need to run the screen.

  • ✓Base-year value and change-of-ownership date pulled for every parcel
  • ✓January 1, 2026 market value modeled against the factored base
  • ✓Filed by Reserve Tax Group under your authorization before Nov 30
  • ✓18% of the savings on wins, nothing otherwise

Free to start. No card required. Strictly confidential.