HighUS

California Sales Tax Audit of E-Commerce Seller

California audited an e-commerce seller for unpaid sales tax across multiple years.

What Happened

California's Board of Equalization conducted a sales tax audit of an e-commerce seller who had nexus through Amazon FBA inventory stored in state warehouses. The seller had not registered for California sales tax. The audit covered 3 years of back taxes, penalties, and interest.

When

2023-2024 (audit period)

Cause

Amazon FBA inventory stored in California created sales tax nexus, but seller did not register or collect California sales tax.

Resolution

  1. 1Received audit notice from California BOE
  2. 2Hired California tax attorney to represent in audit
  3. 3Compiled all Amazon sales data for California customers
  4. 4Calculated back taxes owed for 3-year audit period
  5. 5Negotiated settlement including back taxes, penalties, and reduced interest
Timeline

6-12 months for full audit resolution

Cost

Back taxes + 30% penalty + interest + legal fees ($10,000-50,000+)

Lessons Learned

  • Amazon FBA inventory in a state creates sales tax nexus
  • California actively audits e-commerce sellers with FBA presence
  • Penalties can reach 30% of unpaid tax, plus interest compounding daily

Prevention

  • Determine sales tax nexus in all states where you have FBA inventory
  • Register for sales tax in nexus states before making sales
  • Use sales tax automation tools to manage multi-state compliance

Sources

  • California BOE audit guidelines
  • Multi-state sales tax nexus guidance
  • Amazon FBA inventory location reports

⚠️ This case study is based on publicly available information and has been anonymized (company names, specific amounts, etc. have been modified). For educational reference only — not legal advice.

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