Do I owe US sales tax when selling from Hong Kong to US customers?

The United States has no federal sales tax, but most states and many localities do. In South Dakota v. Wayfair (2018) the US Supreme Court held that a state can require a remote seller to collect sales tax even without a physical presence in the state, so long as there is a substantial connection. Most states then adopted "economic nexus" rules, usually based on a threshold of sales or transactions into the state.

For a Hong Kong seller:

• If you sell through a marketplace such as Amazon, the marketplace facilitator rules in most states mean the marketplace collects and remits tax on those sales.
• If you sell from your own store, you may need to register and collect once you pass a state's threshold.
• Imports of goods into the US are also subject to customs duty and tariff rules, which changed substantially in 2025, including the end of the low-value duty exemption.

The thresholds and rates vary by state and change, so check each state's department of revenue and take advice where you sell significant volumes.