What do I need before filing a property tax appeal?

Your county's filing deadline, your assessment notice with the APN and assessed value, an audit of the assessor's property record for factual errors, your valuation date, and three to five admissible arms-length comparable sales supporting a specific opinion of value.

What's the most commonly skipped step in a property tax appeal?

Checking the assessor's own record of your property. Errors in square footage, bed and bath count, lot size, or condition are the most persuasive evidence available because they're factual rather than a matter of opinion — and if the record understates your property, you want to know before inviting scrutiny.

Do I keep paying property taxes while my appeal is pending?

Yes. Filing an appeal doesn't suspend your bill, and late-payment penalties and interest aren't erased by winning. If your value is reduced, you're refunded the overpayment.

How many comparable sales should I submit?

Three to five strong ones, compared honestly, are more persuasive than a long list. All must be arms-length and fall within the §402.5 window — no sale more than 90 days after your valuation date.

How long does a property tax appeal take?

Typically months. Hearings are often scheduled well after the filing window closes, and under §1604 a California board has up to two years to hear and decide — after which, with some exceptions, your stated opinion of value becomes the assessed value until it rules.

The Property Tax Appeal Checklist: Everything to Do Before You File

Appeal season compresses everything into a few weeks: notices arrive in July, and in the counties with the earliest deadline you have until September 15. Here's the whole sequence in order, with the steps most people skip marked.

1. Confirm your actual deadline

Not the one an article told you — yours.

California regular assessments: the window opens July 2 and closes September 15 or November 30 depending on your county. Only 11 of 58 counties use September 15 — but they include San Francisco, Alameda, and Santa Clara. Most of the state, including Los Angeles, runs to November 30. (Bay Area dates county by county.)
Supplemental or escape assessments: 60 days from the notice's mailing date, any time of year.
King County, WA: July 1, or 60 days from your value-change notice's mailing date, whichever is later. (Seattle specifics.)

Write the date down. Everything else is flexible; this isn't.

2. Read the notice properly

Find your assessed value (land and improvements separately), the assessment type, and the APN. If no notice arrived, contact the assessor — no notice doesn't extend anything. (How to read the notice.)

3. Audit the assessor's record on your property — most-skipped step

Pull the property characteristics the assessor has on file and check every physical fact: square footage, bedrooms and baths, lot size, year built, condition or grade, and any improvements listed.

Two outcomes, both useful:

The record overstates your property. A documented factual error is the most persuasive evidence in any appeal, because it doesn't ask the board to weigh opinions.
The record understates your property. Better to know now. An appeal invites a closer look, and if there's unpermitted work or missing square footage on file, that changes the calculus. (The realistic risks of filing.)

4. Identify your valuation date

Regular/Prop 8 appeal → January 1 lien date
Purchase/base year appeal → date of transfer
New construction → date of completion

This determines which sales you're allowed to use, so settle it before gathering anything.

5. Build the comparable sales — the part that decides the outcome

Everything else on this list is administrative. This is the job.

Arms-length sales only. No foreclosures, family transfers, or distressed sales presented as market evidence.
Inside the §402.5 window. No sale more than 90 days after your valuation date is usable, full stop. In a falling market that excludes the most recent — and lowest — sales. (The 90-day rule.)
Genuinely comparable on location, property type, size, age, condition, and features. Condos to condos, matched on floor, view, and parking. (Why condo cases are strong.)
Three to five strong comps, honestly compared, beats a long list. Look at the ones that don't help you too — the assessor will.

CompFinder does this step for SF, Oakland, San Jose, Seattle, and Issaquah: enter the address, get the screened comp set and written comparison.

6. Size the gap and decide

Compare your supported market value to your assessed value. In California, roughly $1,200 a year per $100,000 of reduction. (Estimating your savings.)

If the gap is meaningful, file. If it's marginal, weigh the filing fee and your time — San Francisco charges $120, other counties less or nothing.

7. Choose your route

Informal review — free, no hearing, but no deadline protection. SF's window (Jan 2 – Mar 31) has closed for the year; Alameda accepts them July 1 – Dec 31.
Formal appeal — independent board, binding, protects your rights.
Both — file formally to protect the deadline, then work with the assessor's office, which often resolves by stipulation without a hearing. This is the safe play in August. (Comparing the two.)

8. File the application carefully

On BOE-305-AH: correct APN, one assessment type checked, an opinion of value you can support (it caps your outcome), agent authorization if anyone else is signing, and — the one people forget — check the claim-for-refund box so a win refunds automatically instead of requiring a separate claim. (Section-by-section walkthrough.)

9. Know what you're entitled to at the hearing

If the property is your principal residence with the homeowners' exemption, §167 puts a rebuttable presumption in your favor — the assessor has to establish their value. Say so at the outset. (What the burden shift means.)

Also: keep paying your tax bill while the appeal is pending. Filing doesn't suspend it, and penalties survive a win.

10. Prepare for the hearing itself

Expect a wait — hearings are often many months out, and the board has up to two years to decide. Bring organized copies, present value only, and stay factual. If you can't attend, request a postponement (in SF, at least 14 days ahead) or send an eligible family member rather than not showing. (Inside an appeals board hearing.) (The timeline.)

Quick version

Confirm your deadline — and whether it's September 15 or November 30
Read the notice; get the APN and assessed value
Audit the assessor's property record for errors
Fix your valuation date
Build 3–5 admissible comps inside the 90-day window
Size the gap
Formal filing protects you; informal doesn't
Check the refund box
Claim the §167 presumption if it's your home
Keep paying the bill

Starting from scratch in California? Begin with the step-by-step guide for San Francisco, Oakland, or San Jose.