Complete guide to ecommerce sales tax. Learn about economic nexus, state tax rates, collection obligations, how to set up tax automation, and stay compliant across the US.
Tax Compliance for Ecommerce: What Every Online Seller Must Know
Ecommerce tax compliance has become dramatically more complex in recent years. In the US, the 2018 South Dakota v. Wayfair decision means you may owe sales tax in states where you have economic nexus — even if you have no physical presence there. Most states use thresholds of $100,000 in sales OR 200 transactions. In the EU, VAT rules for distance selling require registration once you exceed EUR 10,000 in cross-border sales. The EU OSS (One-Stop-Shop) scheme lets you report all EU VAT through a single return. UK, Australia, and Canada have similar rules. Failure to comply can result in penalties, back taxes, and in severe cases, platform suspension. Use a tax automation tool like Avalara, TaxJar, or Quaderno to handle multi-jurisdiction compliance automatically.
Financial Reporting for Ecommerce: Building a Profitable Business
You can't manage what you don't measure. Effective ecommerce financial reporting goes beyond simple profit and loss statements. Essential reports include: gross margin by product/category (identify your most and least profitable products), inventory turnover rate (slow-moving inventory ties up cash and incurs long-term storage fees), cash flow projection (eCommerce has significant cash flow swings due to shipping times, returns, and seasonal demand), and unit economics per SKU (true cost per sale including all fees, shipping, and returns). Review these reports monthly. The best ecommerce operators catch problems early — a product that's profitable on paper but has a 30% return rate might actually be losing money once you account for return shipping and restocking.
US Sales Tax Basics for Ecommerce 2026
| Economic nexus threshold |
Varies by state; typically $100,000 sales OR 200 transactions |
| Average combined rate |
7-9% (state + local) |
| Highest combined rate |
10.25% (Louisiana, followed by Arkansas at 10.5%) |
| Tax-free states |
Oregon, Montana, New Hampshire, Delaware, Alaska (no state sales tax) |
| Tax automation tools |
Avalara, TaxJar, Quaderno, Vertex |
| Marketplace facilitator |
Amazon/eBay/Shopify may collect for you in many states |
Frequently Asked Questions
Do I need to collect sales tax on my ecommerce sales?
US sales tax nexus thresholds vary by state but most follow the South Dakota v. Wayfair ruling: $100,000 in sales OR 200 transactions in the state. Some states have different thresholds. Even if you don't meet these thresholds, voluntary registration may still make sense if your customers are concentrated in a specific state. Use Avalara, TaxJar, or Vertex to automate nexus detection and rate calculation across all 50 states.
What is economic nexus for ecommerce?
EU VAT registration is required when your cross-border B2C sales to EU customers exceed EUR 10,000 per year (the EU OSS threshold). VAT rates vary by country: Germany 19%, France 20%, Italy 22%, Spain 21%, Netherlands 21%, Poland 23%. Register through your home country's tax authority using the OSS scheme to report all EU VAT through a single return. Failing to collect VAT on EU sales can result in penalties and back-taxes.
How do I know which states I need to collect tax in?
UK VAT registration is required when UK-based businesses exceed GBP 85,000 in taxable turnover. For non-UK businesses selling to UK customers, registration may be required once you exceed GBP 0 if you're storing inventory in UK Amazon warehouses (FBA) or have significant UK sales. UK VAT rates are 20% standard, 5% reduced rate (some items), and 0% for most food and children's clothing.
What is the average US sales tax rate?
Ecommerce accounting best practices: use dedicated ecommerce accounting software (Xero, QuickBooks Online with A2X for Amazon, or Wave for startups). Reconcile your payment processor deposits daily. Track COGS accurately using actual product costs, not estimates. Set aside 25-30% of revenue for taxes if you're a US sole proprietor. Review your P&L monthly to catch problems early. Consider hiring a CPA who specializes in ecommerce for quarterly reviews.
How do I automate sales tax collection?
Cash flow management is critical for ecommerce because inventory purchases tie up cash weeks before sales arrive, and returns create cash gaps. Maintain a cash reserve of at least 3 months of operating expenses. Use net-30 supplier terms when possible. Amazon and PayPal disbursements have waiting periods—plan for this in your cash flow projection. Consider a line of credit before you need it, not when you're in a crisis.