Quick Answer
A California sales tax audit follows four stages: (1) notice and initial contact via audit appointment letter and initial IDR; (2) records examination where the auditor reviews sales records, purchase invoices, and resale certificates; (3) sampling and testing (if applicable) where the auditor projects results from a sample period to the full audit period; and (4) assessment via Notice of Determination (CDTFA-345-SP). The short version is that the taxpayer has 30 days from the Notice of Determination to file a Petition for Redetermination. Typical audit duration is 6 to 18 months. Sampling methodology is frequently contestable.1
CDTFA audit in progress? A 15-minute consultation is free.
California sales tax audits are methodical. Understanding each stage and the taxpayer's rights at each allows you to contain scope and protect against unjustified assessments. This chapter walks through the four audit stages.
For audit triggers, see Audit Triggers. For preparation, see Prepare for Audit.
The Four Stages of CDTFA Sales Tax Audit
| Stage | Duration | Key Document2 |
|---|---|---|
| 1. Notice | Instant | Audit appointment letter |
| 2. Records Review | 1 to 6 months | IDRs and audit workpapers |
| 3. Sampling / Testing | 1 to 3 months | Sampling methodology memo |
| 4. Assessment | 2 to 4 weeks | Notice of Determination (CDTFA-345-SP) |
Quick Reference
Jump to stage: notice, records review, sampling, or assessment. For document reference, see CDTFA audit document lookup. 15-min consultation free.
1. Notice and Initial Contact
CDTFA issues an audit appointment letter identifying the audit period, scope, and auditor. First contact typically includes initial Information Document Request.
If this is you: Audit notice received. Document the scope — which periods, which issues. Request Power of Attorney (Form CDTFA-392) through counsel.
Notice Stage Strategy
- Confirm audit notice legitimacy.
- File Power of Attorney (CDTFA-392).
- Identify scope. Period, issues, auditor.
- Organize initial records.
- Engage counsel for material cases.
2. Records Examination
The auditor reviews sales records, purchase invoices, resale certificates, and bank records. Auditor issues IDRs; taxpayer responds with documentation.
If this is you: Auditor has requested extensive documentation. Respond only to specific requests. Do not volunteer additional records beyond scope.
3. Sampling and Testing
For businesses with high transaction volume, CDTFA uses sampling — a representative period projected to the full audit period. Sampling methodology is heavily contestable; good samples produce manageable assessments, bad samples produce inflated ones.
If this is you: The auditor has selected a sample period. Scrutinize it — is it representative? Did it include anomalies? Sample challenges can dramatically reduce assessments.
4. Assessment and Notice of Determination
CDTFA issues Notice of Determination (CDTFA-345-SP) with the proposed assessment. Taxpayer has 30 days to file Petition for Redetermination.
If this is you: Assessment received. Calendar the 30-day deadline. File Petition for Redetermination even on preliminary basis to preserve rights.
Notice of Determination received? 30-day clock is critical. Book immediate consultation.
CDTFA Audit Document Lookup
| Document | Purpose |
|---|---|
| Audit appointment letter | Audit initiation |
| CDTFA-392 | Power of Attorney |
| IDR | Information Document Request |
| Sampling methodology memo | Projection methodology |
| CDTFA-345-SP | Notice of Determination (assessment) |
| Petition for Redetermination | 30-day appeal |
| CDTFA-230 | Resale certificates (evidence) |
| Publication 17 | Appeals Procedures |
CDTFA Statute of Limitations
- 3 years standard.
- 8 years for substantial understatement (25%+).
- No limit for fraud or non-filing.
- Waiver Form CDTFA-122.
- 30-day Petition for Redetermination deadline.
CDTFA Audit Outcomes
| Preparation Quality | Typical Outcome |
|---|---|
| Clean records + professional representation | Minor assessment or no-change |
| Clean records + self-represented | Moderate assessment |
| Poor records | Projected assessment via unfavorable sampling |
| Missing resale certificates | Assessment on resale transactions |
CDTFA Audit Escalation Pathway
Initial Audit to Assessment
Stages 1-4 conclude with Notice of Determination.
Assessment to Redetermination
Petition for Redetermination within 30 days. CDTFA Appeals reviews.
Appeals to OTA
Denial at CDTFA can be appealed to Office of Tax Appeals, then Superior Court.
The First 48 Hours After CDTFA Audit Notice
- Document audit scope and period.
- File Form CDTFA-392 Power of Attorney.
- Pull records for audit period.
- Identify resale certificates, exemption claims.
- Reconcile against federal returns and bank records.
- Schedule initial meeting through counsel.
- Engage sales tax counsel.
The ROI Question
Sampling methodology challenges at CDTFA frequently produce six-figure reductions. Professional representation during audit stages typically saves multiples of the fee.
Facing a California Sales Tax Audit?
CDTFA audits move quickly once a notice arrives. The direction of the audit is largely set by how you handle the initial document request and auditor interview. If you’re at any stage — from notice through assessment — we can review where things stand and identify what options are available.
Discuss My Sales Tax Audit → Or call: (619) 378-3138
When to Engage an Attorney for CDTFA Audit
- Assessment over $50,000.
- Sampling applied.
- Industry-specific audit.
- Out-of-state nexus question.
- Prior CDTFA liability.
Frequently Asked Questions
What happens in a California sales tax audit?
Four stages. Notice (audit appointment letter + initial IDR). Records review (auditor examines sales, purchases, resale certificates). Sampling and testing (for high-volume businesses, projection from representative period). Assessment via Notice of Determination. Taxpayer has 30 days to petition for redetermination.
How long does a California sales tax audit take?
6 to 18 months typical. Simple desk audits: 3 to 6 months. Field audits with sampling: 6 to 12 months. Complex multi-year or multi-location audits: 12 to 24 months or longer.
What is CDTFA sampling in audits?
A statistical projection method. The auditor examines a representative sample period (typically 1-3 months) and projects the results to the full audit period. Used for high-volume retailers where examining every transaction is impractical. Sampling methodology is heavily contestable.
How do I respond to a CDTFA IDR?
Provide only the records specifically requested. Do not volunteer additional documentation. Request extensions in writing before the deadline. Route responses through counsel where material. Incomplete IDR responses produce worst-case auditor assumptions.
What is a Notice of Determination?
CDTFA-345-SP — the formal assessment notice at the conclusion of a sales tax audit. Identifies the assessed tax, penalties, and interest. Triggers the 30-day Petition for Redetermination deadline. Missing the deadline makes the assessment final.
Can I appeal the CDTFA audit findings?
Yes. Petition for Redetermination within 30 days. CDTFA Appeals reviews first. Further appeal to Office of Tax Appeals (OTA). Ultimately Superior Court review is available. Each level has specific procedures and deadlines.
What records does CDTFA typically request?
Sales records (invoices, receipts, Point-of-Sale reports). Purchase records (invoices, resale certificates). Bank deposits. Credit card processor reports. Federal tax returns. Exemption certificates (CDTFA-230 resale, other). For specific industries, additional records (inventory, depreciation schedules).
Can I challenge CDTFA sampling methodology?
Yes. Common challenges include unrepresentative sample period, insufficient sample size, anomalies in sample that skew results, and projection errors. Successful sampling challenges can dramatically reduce assessments. This is a frequent area of CDTFA dispute.
Do I need a lawyer for a CDTFA audit?
For assessments over $50,000, yes. For smaller desk audits with clean records, possibly not. Sampling applied or resale certificate issues materially benefit from counsel. A 15-minute intake call identifies the right approach.
What if I disagree with the auditor's findings?
File Petition for Redetermination within 30 days of the Notice of Determination. CDTFA Appeals reviews. Challenges to specific calculations, sampling methodology, or legal interpretations can produce meaningful reductions.
Does CDTFA collect during an audit?
Not during the audit itself. Collection authority triggers on the Notice of Determination and becomes enforceable if the 30-day Petition window closes without filing. Pre-assessment collection is rare.
Can CDTFA levy during audit disputes?
Generally not while a Petition for Redetermination is pending. Collection resumes only after the petition is denied and the assessment becomes final. Judicial review paths (OTA, Superior Court) can further delay collection.
What is the CDTFA audit discovery process?
CDTFA issues IDRs requesting specific records. The taxpayer may have the right to request the auditor's workpapers and internal analysis. Reciprocal discovery is common in complex audits and is essential for understanding the assessment basis.
Next Steps in This Guide
If CDTFA audit in progress, a 15-minute consultation is free.