Blog/US Business Setup

US Sales Tax Economic Nexus for Overseas E-commerce & SaaS Companies

A comprehensive state sales tax compliance masterclass for international e-commerce sellers, Shopify merchants, Amazon FBA brands, and SaaS founders on Wayfair economic nexus thresholds and permit registration.

ADVAQ US Tax Team
8 Min Read · Published July 2026
Wayfair Economic Nexus Compliant
Economic Nexus Key Rules
  • Wayfair Supreme Court Ruling: States can require foreign sellers with zero physical presence to collect state sales tax if they cross economic sales thresholds.
  • $100,000 Threshold: Most states enforce an Economic Nexus threshold of $100,000 in gross annual sales or 200 separate transactions into that state.
  • Amazon Marketplace Facilitator: Amazon automatically collects sales tax on FBA sales. Independent Shopify & Stripe sellers must handle registration manually.
  • SaaS Taxability: SaaS and digital goods are taxable in ~30 US states (e.g. Texas, New York, Pennsylvania).

1. The Wayfair Supreme Court Ruling & Economic Nexus

In June 2018, the US Supreme Court issued a historic ruling in South Dakota v. Wayfair, Inc., eliminating the physical presence requirement for state sales tax collection.

Today, 45 US states and Washington D.C. enforce Economic Nexus laws. If your foreign business sells goods or digital services to customers in a state and exceeds that state's economic threshold, you must register, collect, and remit state sales tax.

2. State-by-State Revenue Threshold Breakdown ($100k Rules)

Standard Economic Nexus thresholds:

  • Most States (e.g. Florida, Texas, Illinois): $100,000 in gross annual sales into the state.
  • High Threshold States (e.g. California, New York): $500,000 in gross annual sales.

3. Amazon vs Shopify: Marketplace Facilitator Laws

If you sell products primarily on Amazon FBA, eBay, or Walmart Marketplace, marketplace facilitator laws require the platform to calculate, collect, and remit sales tax automatically.

However, if you sell directly via your own Shopify, WooCommerce, or Stripe SaaS billing portal, you are solely responsible for calculating and remitting sales tax once economic nexus is reached.

US SALES TAX ADVISORY

Get Your US Sales Tax Permits with ADVAQ

ADVAQ conducts state economic nexus audits, registers sales tax permits across all 50 states, and integrates automated tax collection with Stripe and Shopify.

4. Taxability of SaaS and Digital Products in the US

SaaS taxability varies drastically by state:

  • Taxable States for SaaS: Texas, New York, Pennsylvania, Washington, Massachusetts.
  • Exempt States for SaaS: California, Florida, Georgia, Virginia.

5. How Foreign Sellers Register for State Sales Tax Permits

Before collecting sales tax from US customers, you must register for a Sales Tax Permit with that state's Department of Revenue using your US LLC EIN. Collecting sales tax without a permit is illegal.

Frequently Asked Questions

US SALES TAX SOLUTIONS

Manage US Sales Tax Compliance with ADVAQ

Economic nexus auditing, state sales tax permit registration, Shopify/Stripe automated setup, and quarterly filings.