Sales Tax Nexus for Online Sellers, Explained
Since the Wayfair decision, you can owe sales tax in states you have never set foot in. Here is what nexus means, when crossing a state's threshold forces you to collect, and why marketplace sales are their own puzzle.
For a long time, the rule for online sellers was simple: you only had to collect a state's sales tax if you had a physical presence there. Then a 2018 Supreme Court case rewrote it, and now you can owe sales tax in states you have never visited, triggered by nothing more than how much you sell into them. It is one of the most misunderstood parts of running an ecommerce business, and getting it wrong can mean a surprise bill for years of uncollected tax.
What nexus actually means
Nexus is just the connection between your business and a state that is strong enough for the state to require you to collect its sales tax. There are two flavors. Physical nexus is the old kind: an office, employees, or inventory in the state, and yes, stock sitting in an Amazon warehouse counts. Economic nexus is the newer kind, based purely on your sales volume into the state.
The Wayfair decision changed the game
In South Dakota v. Wayfair, the Supreme Court let states require out-of-state sellers to collect sales tax based on economic activity alone. A common threshold is 100,000 dollars in sales or 200 transactions into a state in a year, but and this is the part that trips people up, the exact numbers vary widely by state. Some use a higher dollar figure, some have dropped the transaction count entirely, and they change the rules over time. There is no single national number, so you check each state where you have meaningful sales.
The marketplace wrinkle
If you sell through Amazon, eBay, or Etsy, marketplace facilitator laws make the platform collect and remit the sales tax for you in nearly every state. That is a real relief, and it is the same reason your Amazon bookkeeping and eBay bookkeeping generally do not involve you remitting that tax. But two things still bite. In some states, those marketplace sales count toward your own economic-nexus thresholds, and the moment you sell on your own website, you are the one responsible for collecting and remitting.
What to actually do
- Track your sales by state so you can see when you are approaching a threshold.
- Register for a sales tax permit in each state where you have nexus before you start collecting.
- Collect the tax at checkout and file on the state's schedule, which can be monthly, quarterly, or annual.
- Do not ignore it, because states can assess back tax, penalties, and interest reaching back to when nexus began.
Because the thresholds and rules shift constantly, this is an area where confirming with a state revenue department or a sales tax specialist pays for itself.
See your sales by state before nexus sneaks up
Vuuv organizes your sales channel by channel, so you can spot where your volume is climbing and stay ahead of your collection duties.
Start freeHow Vuuv helps
Nexus is a tracking problem before it is a tax problem, and that is where Vuuv helps. By pulling your sales together and keeping them organized, it gives you a clear picture of where your money is coming from, so a state quietly creeping toward its threshold does not catch you off guard. Combined with the 1099-K reporting we cover in our online seller guide, you get one place to understand both what you owe and where.
Frequently asked questions
What is sales tax nexus?
Nexus is the connection between your business and a state that is strong enough for the state to make you collect its sales tax. It used to require a physical presence like an office, employees, or inventory. Since 2018, it can also be triggered purely by how much you sell into a state, with no physical presence at all.
What is economic nexus and the Wayfair rule?
In the 2018 South Dakota v. Wayfair decision, the Supreme Court let states require out-of-state sellers to collect sales tax based on sales volume alone. A common threshold is 100,000 dollars in sales or 200 transactions into a state in a year, but the exact numbers vary a lot by state, and many states have changed or dropped the transaction count. You check each state where you sell.
Do I collect sales tax if I only sell on Amazon or eBay?
Usually not on those sales. Marketplace facilitator laws make the platform collect and remit the sales tax for you in nearly every state. The catch is that in some states those marketplace sales still count toward your own nexus threshold, and the moment you sell on your own site, you are responsible for collecting directly.
What happens if I ignore sales tax nexus?
It does not go away. If a state later decides you had nexus and were not collecting, it can assess the back tax you should have collected, plus penalties and interest, sometimes reaching back to when nexus was first triggered. Sorting it out early is far cheaper than getting a bill for years of uncollected tax.
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This article is general information, not tax advice. Tax rules change and every situation is different. Confirm the details against current IRS guidance or talk to a qualified tax professional before you file.