Where do I get the BOE-305-AH form?

From the Clerk of the Board in the county where the property is located — counties issue their own version with local filing instructions and fees. Many now offer online filing. The State Board of Equalization's Publication 30, Residential Property Assessment Appeals, walks through the form as well.

What is the claim-for-refund box on the appeal application?

An option to designate your application as a claim for refund. If you check it and win, the county processes the refund automatically. If you don't, you must file a separate claim-for-refund form afterward, which has its own deadlines.

How much does it cost to file a property tax appeal in California?

It depends on the county. San Francisco charges a $120 non-refundable filing fee. Other counties charge a smaller processing fee or nothing at all — check the application your county issues.

Can someone else file and present the appeal for me?

Yes, but unless they're a licensed California attorney, the application needs a completed agent authorization. In California a spouse, parent, or adult child can also typically appear on your behalf — confirm with the Clerk of the Board.

How to Fill Out California's Assessment Appeal Application (Form BOE-305-AH)

Q: What should I put as my opinion of value?

A figure supported by arms-length sales of comparable properties near the January 1 lien date. Treat it as a ceiling: boards rarely reduce a value below what the applicant requested, so an unsupported guess either caps your savings or costs you credibility.

California's appeal application is two pages and takes about fifteen minutes. Two of the boxes on it have consequences that last the entire appeal, and they're the two people fill in casually.

Get the form from your county, not the internet

The statewide form is BOE-305-AH, Assessment Appeal Application, but you must file the version issued by the Clerk of the Board in the county where the property sits — counties add their own filing instructions, fee, and submission portal. Most Bay Area counties now accept online filing. San Francisco charges a $120 non-refundable fee; other counties charge less or nothing.

Sections 1–3: identifying you and the property

Straightforward, with one caution:

Applicant information. Use the name and mailing address as they appear on the tax bill. If the owner of record is a trust, the applicant should match the record.
Agent authorization. If anyone other than you signs or presents — a consultant, a tax agent, a relative — the form needs an agent authorization. A licensed California attorney is the exception. (Do you need to hire anyone?)
Property identification. The Assessor's Parcel Number (APN) exactly as printed on your bill, plus the address. A wrong APN is the most common reason an application gets bounced.

Section 4: value on roll vs. your opinion of value

This is the one that matters. You enter the assessed value currently on the roll (land and improvements, from your notice or bill) and, beside it, your opinion of value.

Treat that number as a ceiling. Boards rarely reduce a value below what the applicant themselves asked for, so an opinion you picked optimistically before looking at any sales data becomes the cap on your own outcome. Two failure modes:

Too high — you leave money on the table you can't recover later.
Absurdly low — you lose credibility with a panel that sees this constantly, and the assessor's comps look reasonable by comparison.

Derive it from actual arms-length sales of similar homes near the January 1 lien date before you type it in. Sales dated more than 90 days after the lien date can't be used as comparables at all (§402.5), which rules out a lot of what a public listing site will show you. (How to select and adjust comps.) This is exactly what CompFinder produces for SF, Oakland, San Jose, Seattle, and Issaquah.

Section 5: type of assessment — check one box

Only one, and it determines your deadline:

Regular assessment — the annual roll value. Filed in the July 2 window (which closes September 15 or November 30 depending on your county).
Supplemental assessment — from a purchase or new construction. 60 days from the notice's mailing date.
Escape assessment — value the assessor added after the fact. Also 60 days.
Decline in value (Prop 8) — the temporary reduction most homeowners in a soft market are actually after. (What Prop 8 is.)

Section 6: reasons for the appeal

Keep it short and factual. "The assessed value exceeds market value as of the January 1 lien date, based on comparable sales" is a complete and sufficient reason. You are not writing your argument here; you present that later. Don't editorialize about tax rates, city spending, or your neighbor's assessment — none of it is a legal ground for reduction.

The box people forget: claim for refund

Somewhere on the application is an option to designate it as a claim for refund. Check it.

If you do, and you win, the county processes your refund automatically. If you don't, you have to file a separate claim-for-refund form afterward to get money you've already been awarded — and refund claims have their own time limits. It's a checkbox that costs nothing and prevents the most avoidable loss in the process. (How refunds actually arrive.)

Before you submit

Confirm: correct APN, one assessment type checked, an opinion of value you can support with sales, refund box checked, signed, fee included, and postmarked or submitted on or before your county's closing date. Then keep a copy — the hearing may be many months out, and the two-year rule starts running from the date you filed.