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How to Know When It’s Time to Register for U.S. Sales Tax | TaxValet

Written by Richard Reynolds | Jan 13, 2026 9:16:31 AM

They say the USA is the land of opportunity. And YES, the opportunity for massive revenue is real. 

But it is also home to thousands of conflicting tax codes, each with its own registration rules. For international businesses selling into the States, knowing when to register for a sales tax permit can be a massive headache

This guide explains when international sellers should register in each state, how to identify nexus triggers, and the specific steps to take to be compliant.

 

When Do I Need to Register for U.S. Sales Tax?

Your U.S. sales tax obligation starts the moment your business establishes sales tax nexus. 

Sales tax nexus exists when a business’s presence or activity in a state triggers a sales tax obligation. It’s formed when you cross a certain activity threshold, like more than $100,000 in gross sales, obligating you to collect and remit sales tax.

Sales tax nexus can be triggered in many ways, like:

  • Physical business activity in a state
  • Revenue activity 
  • Advertising
  • Generating click-throughs from local affiliates
  • And more

When you need to register for sales tax depends on the nexus trigger your business hits, and the jurisdiction you operate in:

  • Some states expect registration immediately when the trigger occurs. 
  • Others set clear timelines after a business crosses a threshold, like 30 days. 

Some jurisdictions also expect you to register for sales tax even if you sell exclusively through a marketplace. This can apply even if the marketplace collects sales tax on your behalf.

 

Do I Need to Register for U.S. Sales Tax if I’m Outside the U.S.? 

Selling from outside the U.S. doesn’t prevent you from triggering sales tax nexus. Neither do treaties or home-country tax rules. 

The states also don’t consider your foreign status a reason to delay or avoid sales tax registration.

In other words, as a foreign seller, you’ll still need to register for sales tax if you hit nexus in a state. Focus on where your customers are in the U.S., not necessarily your business address. 

 

Sales Tax Nexus for Foreign Sellers

Now, let’s talk about the nexus triggers that you, as a foreign seller, need to be aware of.

 

Physical Triggers That Create Nexus

Physical presence is the traditional sales tax nexus trigger. And unlike other types of nexus, it can be triggered even with one instance of physical presence in the state.

Physical activity is defined in various ways, like: 

  • Storing goods in a warehouse or fulfillment center. 
  • Having a single payroll employee or contractor working in a state. 
  • Using independent agents, affiliates, or representatives to establish or maintain a market.
  • Attending trade shows or industry events. Some states allow a few days of activity without penalty, but others require registration the moment you set up a booth.
  • Sending staff or subcontractors to a state to install equipment or repair products.
  • Owning or renting any real estate, such as a small office or a showroom.

However, rules vary by state. Some states apply safe harbor rules that exclude limited, temporary physical activities from creating nexus. Others deem even one physical activity or a few hours of presence enough for you to owe sales tax. Check the rules in the states you sell in to understand what it means for you.

 

Economic Triggers That Create Nexus

Unlike physical nexus, economic nexus is based solely on the volume of your business’s sales or transactions (sometimes both) within the state. Here, you’re mostly looking at whether your sales activity crosses a state’s economic threshold. 

Across the country, threshold limits vary, but they tend to fall into two different categories: 

  • Most states use a revenue threshold between $100,000 and $500,000.
  • A handful of states also use transaction counts, like making 200 separate sales.

Most states use either a revenue or transaction threshold. However, some states apply both, and whichever one you trigger first creates sales tax nexus.

What counts toward those limits depends on the state. Some measure total gross sales. Others carve out specific activity, such as wholesale orders, marketplace facilitated sales, or exempt transactions.
 
 
 
 

Economic Nexus Thresholds by State for 2025 

You might think calculating when you cross a threshold is easy, but the measurement periods make things tricky. Most states check your activity based on the current or prior calendar year, but there are some that go with a rolling 12-month period or quarterly.

Then there is New York. It uses its own quarterly structure ending in May, August, November, and February, which doesn’t match any other state.

Check the measurement rules for each state before mapping out exposure, or when a new obligation kicks in. And if you’re a foreign seller, you need to track these totals in dollars.

 

 

What is a Trailing Nexus?

 It is natural to assume you can close your sales tax permit the moment your sales dip below the threshold in a state. But some states apply a concept called the ‘trailing nexus’. It means a state might require you to keep filing returns for a set period, often a full year or more, after you stop doing business there. 

They reason that your marketing or brand presence continues to influence sales even after you physically leave or stop hitting the numbers. 

Trailing nexus rules vary by state, and not all states clearly publish their position. Some require continued filing for a defined period, while others have expressly stated they do not apply trailing nexus. When a state has not clearly stated its rule, continue filing zero returns until the account is formally closed to avoid missed filing penalties.

 

The Double Work of Home-Rule States

In most of the U.S., one state registration covers every city and county inside it. You sign up with the state, and you are done.

But Home Rule states like Colorado, Louisiana, and Alabama play by different rules. In these areas, local jurisdictions (like specific cities) have the power to administer their own taxes.

While they aren’t the only states with tricky local tax nuances, these Home-Rule areas generally require you to register separately with each local authority. If you miss these local requirements, you’re technically non-compliant, even if your state account is set up correctly.

 

The 3 Ways to Register

Once you know where you have sales tax nexus, you’ll have to decide how to handle the paperwork. 

You generally have three paths:

1. First, you can register directly with each state. Going solo is the “free” option, but it’ll cost you time and, in the long run, resources. You’ll have to hop between different websites, juggle a bunch of unique logins, and figure out a ton of specific forms for each area. You’ll also likely have to figure out where you owe sales tax, when to file, what to classify as taxable, etc.
 
2. Second, you can use the Streamlined Sales Tax (SST) system. This centralizes registration for member states into one application. It is efficient, but it has limits. It doesn't cover massive economic hubs like New York or California, so you will still likely end up managing multiple systems.
 
3. Third, you can hire an expert sales tax partner like TaxValet. In this case, a specialized company takes care of the applications, manages your secure data, and makes sure those sneaky traps we covered above won't snag you later.
 
 
 
 

Let Us Handle the Mess

You didn't build your company because you have a passion for state statutes. You built it to solve a problem and serve your customers.

But success in the U.S. market comes with sales tax complexity. 

At TaxValet, we help you replace the confusion with confidence. Compliance stays intact without adding work to your plate. Registration, filing accuracy, and ongoing liability stop interfering with growth.

If you’re ready to stop worrying about this complex field, let’s talk.

 

FAQs

 

What happens if a business registers late for sales tax? 

Registering late without a plan for your sales tax is dangerous. By doing so, you open yourself up to potential scrutiny and increased liability. If a state discovers you have been active without registering, they can assess tax, penalties, and interest going back to when your activity first started.

 

Does a foreign seller need a U.S. bank account for sales tax?

Technically, no, but practically, yes. Most states require electronic payment (ACH) from a U.S. bank. You can sometimes wire funds internationally, but fees are high and errors are common. Services like Payoneer or Wise are often the best middle ground.

 

Does a foreign business require a U.S. entity to register for sales tax?

No. You do not need to form a U.S. LLC or Corporation. You can register as a foreign entity using your home country's details, though you will need a federal EIN first.

However, you should strongly consider obtaining an Individual Taxpayer Identification Number (ITIN) for a responsible party in your business. While not strictly required by federal law to do business, some states (like Florida and Virginia) effectively block online registration if the responsible party does not have an SSN (Social Security Number) or ITIN (individual Taxpayer Identification Number).

 

How do states notify foreign sellers of changes to their sales tax obligations? 

They usually send paper mail to the address on file. Since international mail is slow and unreliable, you must create online logins for every state you register in and check their message centers often.

 

Do tax treaties influence U.S. sales tax rules? 

No. International income tax treaties (like the US-UK treaty) apply to federal income tax, not state sales tax. They offer you no protection here. You will still need to register for sales tax in a relevant state if you trigger nexus there.

 

How does sales tax nexus apply when using multiple warehouses?

If you have inventory in multiple states (even through Amazon FBA), you likely have physical nexus in all those states.