The Myth of the “Ocean Barrier”
The most dangerous assumption a UK seller can make is that being based in London, Manchester, or Birmingham protects them from the Internal Revenue Service (IRS) or state-level tax departments. Many believe that if they don’t have an office in New York or a shop in California, they don’t owe US taxes.
This is false.
In 2018, a landmark Supreme Court case (South Dakota v. Wayfair, Inc.) changed everything. It allowed states to tax remote sellers based on their economic activity alone. Today, your physical location is almost irrelevant. If you sell enough to customers in a specific state, that state expects its cut.
What is Nexus? Your Legal Connection Defined
“Nexus” is simply a fancy legal term for a “significant connection.” If you have nexus in a US state, you are legally required to register for a sales tax permit, collect tax from your customers, and remit that tax to the state government.
There are four primary ways a UK business triggers nexus:
1. Economic Nexus (The Most Common Trigger)
Economic nexus is triggered once you exceed a certain threshold of sales or transactions within a state. Most states have settled on a “100/200” rule:
- $100,000 in gross sales OR
- 200 separate transactions
If you hit either of these in a calendar year, you have nexus. However, be careful, some states like California and Texas have a much higher threshold of $500,000. Don’t worry about memorizing every state yet; the key is to monitor your data.
2. Physical Nexus (The Inventory Trap)
You might think you have no physical presence in the US, but if you use Amazon FBA or a third-party logistics (3PL) provider, you likely do. Storing inventory in a warehouse owned by someone else still counts as physical nexus in many states. If your goods are sitting in a warehouse in New Jersey, you have a physical connection to New Jersey.
3. Marketplace Nexus
If you sell exclusively through “Marketplace Facilitators” like Amazon, eBay, or Etsy, these platforms are often required to collect and remit sales tax for you. This is a huge relief, but it doesn’t always absolve you of the requirement to register or file “zero-tax” returns.
4. Click-Through and Affiliate Nexus
Do you pay a US-based influencer or an affiliate website to link to your products? If that affiliate is in a state with “click-through nexus” laws, their presence could be attributed to you, triggering tax obligations.
Why “Wait and See” is a Dangerous Strategy
We often hear UK sellers say, “I’ll wait until I’m bigger before I worry about US taxes.” This is a recipe for financial disaster.
State tax authorities are increasingly aggressive in pursuing overseas sellers. Unlike the UK’s VAT system, which has a unified national threshold, the US system is fragmented across 45 states (plus D.C.), each with its own rules. If you fail to register when you hit nexus, the state can come after you for back taxes, penalties, and interest.
Because sales tax is meant to be collected from the customer at the point of sale, if you don’t collect it, the state will still demand it, and it will come directly out of your profit margins. Doing this will save you time and protect your bottom line in the long run.
Managing Multi-State Compliance: A Checklist for UK Sellers
Navigating 45 different sets of rules is a full-time job. This is why systematic compliance processes are essential for businesses handling multi-state obligations.
Here is the step-by-step process to ensure you stay in the clear:
- Analyze Your Sales Data: Review your historical sales across all US states to identify where you have already hit thresholds.
- Register for Sales Tax Permits: You must register before you start collecting tax. Collecting tax without a permit is illegal.
- Update Your Website/Marketplace: Ensure your checkout process (Shopify, Magento, etc.) is configured to calculate the correct tax rate based on the customer’s zip code.
- Keep Exemption Certificates: If you are a B2B seller, you may not need to collect tax if your customer provides a valid resale certificate. Keep these on file!
- File Returns On Time: Each state has its own filing frequency (monthly, quarterly, or annually). Missing a deadline results in automatic fines.
US Sales Tax vs. UK VAT: Key Differences
To help you simplify these complex topics, here is a quick comparison:
| Feature | UK VAT | US Sales Tax |
|---|---|---|
| Authority | National (HMRC) | State & Local (e.g., California, NY) |
| Threshold | £90,000 (usually) | Varies (often $100,000 or 200 orders) |
| Tax Type | Value-Added (Every stage) | Consumption (Final sale only) |
| Pricing | Usually included in price | Usually added at checkout |
Key Takeaways for UK Sellers
Expanding to the US market is achievable, but it requires understanding the nexus rules that apply to your specific business model. The sooner you address US sales tax compliance, the sooner you can scale confidently without fear of state audits or back-tax liabilities. Remember, you are still required to declare your global profits to HMRC alongside any US tax obligations.
