CDTFA Audit Appeal Process Explained

Receiving a CDTFA Notice of Determination doesn't mean you've run out of options. California law gives taxpayers the right to contest audit findings — and businesses that pursue appeals with proper representation frequently achieve meaningful reductions in their assessed liabilities.

When does the right to appeal arise?

The formal appeal process is triggered when the CDTFA issues a Notice of Determination (NOD) — the official document stating your assessed sales tax liability, penalties, and interest after an audit. You have 30 days from the date of the NOD to file a Petition for Redetermination. This deadline is firm. Missing it significantly limits your options and can result in the assessment becoming final and collectible.

Stage 1: Petition for Redetermination

The first formal appeal step is filing a Petition for Redetermination with the CDTFA. This document formally contests the NOD, identifies which aspects of the assessment you dispute, and preserves your appeal rights while the matter is reviewed. Filing the petition halts collection action during the appeal so no payment needs to be made towards the asserted liability while it is under dispute.

Stage 2: CDTFA Appeals Bureau review

After the petition is filed, the matter is assigned to the CDTFA's Appeals Bureau — a separate unit from the auditing division, staffed by attorneys and tax professionals who conduct an independent review of the case.

During this stage, you (or your representative) attend an informal oral hearing, submit a written brief laying out your legal and factual arguments, the auditing division submits a response, and the Appeals Bureau issues a Decision either granting or denying the appeal. This stage can take anywhere from several months to over a year depending on case complexity.

What makes a strong CDTFA appeal?

Strong appeals typically involve one or more of the following:

• Legal errors. The auditor misapplied California sales tax law — for example, treating exempt sales as taxable.
• Methodological errors. The auditor's sampling or estimation technique was statistically flawed, or did not accurately represent your actual sales patterns.
• Documentation errors. Records exist that the auditor did not consider or were not provided.
• Penalty disputes. Even when the underlying tax assessment is accurate, penalties may be disputed if you can demonstrate reasonable cause.

Stage 3: Office of Tax Appeals (OTA)

If the CDTFA Appeals Bureau review does not resolve the dispute satisfactorily, you can appeal further to the California Office of Tax Appeals (OTA) — an independent agency that replaced the former Board of Equalization's appeals function in 2018.

The OTA conducts de novo review, meaning it examines the case fresh. The OTA process involves filing a formal appeal within 30 days of the Appeals Bureau's decision, submitting written briefs, and an oral hearing before a three-member panel of administrative law judges. OTA decisions can be appealed further to California Superior Court.

Penalties and interest during an appeal

Interest on the assessed liability generally continues to accrue during the appeal process. This is an important consideration when evaluating whether to appeal and how aggressively to pursue each stage. However, the prospect of reducing a large principal assessment can make the accruing interest worthwhile — particularly when the underlying methodology is significantly flawed.

What happens if you don't appeal?

If no petition is filed within 30 days of the NOD, the determination becomes final. The CDTFA can then begin collection action — including filing liens against your business and personal assets, levying bank accounts, and in some cases revoking your seller's permit.

Should you appeal?

Not every audit determination warrants a formal appeal. The decision depends on the size of the assessment relative to the cost of pursuing an appeal, whether there are genuine legal or factual errors in the determination, the strength of your supporting documentation, and the penalties and interest at stake. A qualified California sales tax consultant can help you evaluate the merits of your case honestly before you commit to an appeal strategy.

The bottom line

The CDTFA appeal process exists precisely because audit determinations are not always correct — and California has built multiple layers of review to give taxpayers a fair opportunity to contest them. Businesses that engage experienced representation and build well-documented appeals regularly achieve significant reductions. If you've received a Notice of Determination you believe is wrong, the 30-day clock is running. Don't wait.