Key Takeaways:
- Nexus ties your business to a state’s sales tax rules. Once it exists, you’re on the hook to collect and remit.
- Sales tax nexus has two definitions: physical (warehouse, staff, or inventory in a state) and economic (you’ve crossed that state’s revenue or transaction threshold).
- The 2018 Wayfair decision opened the door for states to require tax collection based on sales volume alone, no office or warehouse needed.
- Ecommerce tax nexus exposure grows quietly as your business scales, making periodic reviews a genuinely useful habit.
If you’ve ever searched “sales tax nexus” and quietly wondered what it actually means, you’re not alone. Most ecommerce sellers don’t give it much thought until a state notice shows up, which is a terrible time to start learning. The earlier you sort out where you have nexus, the fewer problems you’ll deal with later.
What is Ecommerce Compliance and How Does it Work?
The word itself is Latin, meaning “link.” In tax terms, it’s the trigger that obligates your business to collect and remit in a given state. No nexus, no obligation to collect tax. But knowing whether you’ve triggered that obligation is hard, and it’s why nexus rules are what catches sellers off-guard the most; the ways are much broader than most people expect.
States have a strong interest in collecting tax revenue, and the rules around nexus have expanded steadily to reflect that. There are two main categories every ecommerce seller should understand.
Physical Nexus vs. Economic Nexus
Physical Nexus
Physical nexus is the older definition of tax connection. You have it when your business has a tangible presence in a state. That includes:
- An office, store, or other business location
- Employees or contractors who work in-state
- Inventory stored in a warehouse or fulfillment center is included in physical nexus for sales tax: any 3PL holding your stock.
The last two ecommerce sales tax nexus trips-up a lot of sellers. If Amazon stores your products in a warehouse in, say, Ohio or Pennsylvania, you may have physical nexus in those states even if you’ve never once visited them.
Economic Nexus
Economic nexus is newer and, honestly, the one that matters most. How does this work for tax for ecommerce? Instead of requiring a physical footprint, it’s triggered when your sales into a state cross certain thresholds, most commonly $100,000 in annual revenue or 200 transactions in a calendar year, for sales tax. What is the nexus threshold by state?
Some states only look at revenue. Others use transaction counts. A handful use both. And the period they measure (calendar year vs. rolling 12 months) can vary, too.
The Wayfair Decision: Why the Rules Changed
Before 2018, a Supreme Court ruling, Quill Corp. v. North Dakota, had long protected out-of-state sellers from having to collect sales tax in states where they had no physical presence.
Then came South Dakota v. Wayfair. In 2018, the Supreme Court reversed course, holding that states could require out-of-state sellers to collect sales tax. This created a new sales tax nexus definition, and the state nexus for sales tax – what is South Dakota’s $100,000 in revenue or 200 transactions, quickly became the template most states adopted.
Within about two years, nearly every state with a sales tax had enacted its own economic nexus rules. Selling nationally was no longer a tax-collection workaround.
How Sellers Create Ecommerce Nexus… Accidentally
How does sales tax nexus for ecommerce work? It can build up accidentally. A few of the most common triggers:
- Using Amazon FBA. Amazon moves inventory between fulfillment centers for speed and efficiency. That can put your stock in states you never chase, creating a physical nexus automatically.
- Hiring remotely can trigger it. What is sales tax nexus for hiring people? Working in another state can establish physical nexus there, even if they’re just doing customer service.
- Outgrowing economic thresholds. A strong product launch, a viral moment, or a well-run ad campaign can push you past a state’s economic threshold faster than you’d expect.
- Adding a 3PL. Third-party logistics locations become your nexus locations. Every new fulfillment hub is a potential new state obligation.
What You’re Actually Required to Do
Once nexus is established in a given state, you’re generally looking at three things to stay compliant with what is a state’s sales tax nexus rules:
- Get a permit, sometimes called a Certificate of Authority, before you can legally collect. You can understand the sales tax nexus definition, but you still need paperwork!
- Collect the right rate. Rates are based on the buyer’s location.
- File and remit on schedule. States assign you a filing frequency (monthly, quarterly, or annually) based on how much you’re collecting.
Skipping registration or collecting without remitting carries risks. States aren’t shy about stacking penalties and interest on top of the amount owed.
Keeping Ecommerce Sales Tax Nexus Exposure Under Control
How does sales tax nexus control for ecommerce work? First, determine what nexus exposure for sales tax is – Your fulfillment footprint changes, your sales volume shifts, new states hit threshold – it moves with the business. A few habits that help:
- Run a nexus review at least annually, more often during high-growth periods
- Keep a running tally of sales by state so you can see thresholds coming before you cross them
- Any time you add a warehouse, switch 3PLs, or list on a new marketplace, check how that affects your nexus map
The earlier you catch a new nexus trigger, the safer you’ll be!
Don’t Let It Become a Bigger Problem Than It Needs to Be
Sales tax for nexus is what keeps ecommerce businesses up at night, but it’s manageable – despite requiring consistent attention. The rules vary by state, they change over time, and they accumulate as your business grows; knowing the sales tax nexus definition and current rules isn’t enough.
RJM Tax Exemption works with ecommerce sellers to get ahead of exactly this kind of exposure, from initial nexus reviews through registration, collection setup, and ongoing compliance. Book a free consultation to see how we can handle Nexus!
