Sales Tax Nexus for E-Commerce: Complete 2026 Guide

You built a store, the orders started arriving from thirty states, and somewhere in the back of your mind a question has been growing: am I supposed to be collecting sales tax on all of this? For most e-commerce sellers the honest answer is "in more states than you think, but fewer than you fear." This guide explains how nexus actually works in 2026, which thresholds matter, what the marketplaces handle for you, and how to clean up if you're behind.

What is sales tax nexus — and why did one court case change everything?

Nexus is the connection between your business and a state that gives the state the right to make you collect its sales tax. For decades, only physical presence counted — a warehouse, an office, an employee. Then came South Dakota v. Wayfair (June 2018): the Supreme Court ruled that pure economic activity is enough. Every state with a sales tax responded with economic nexus laws — cross a dollar (or transaction) threshold of sales into the state, and you must register and collect, no physical presence required.

Physical presence still counts too, and e-commerce sellers create it in non-obvious ways: inventory sitting in a third-party warehouse (including marketplace fulfillment centers), a remote employee, even regular trade-show attendance in some states. Economic thresholds get the headlines; physical nexus quietly catches at least as many sellers.

What are the economic nexus thresholds in 2026?

The baseline, modeled on South Dakota's law, is $100,000 in annual sales into the state — and that single number covers most of the map. The clear 2026 trend: states keep dropping the old "200 transactions" test (by industry tallies, roughly 16 states had eliminated transaction counts as of January 1, 2026 — Illinois among the newest, with Kentucky's repeal taking effect August 1, 2026), leaving clean revenue-only thresholds. A representative sample:

Details differ underneath the numbers — states measure gross vs. retail vs. taxable sales, and use the previous calendar year, current year, or a rolling 12 months. Florida, for instance, looks at prior-calendar-year taxable sales, so a seller of mostly exempt goods might stay under its threshold on $200,000 of shipments. Verify the exact test in any state where you're close to the line; thresholds also continue to change year to year.

A note for Florida-based sellers: having your business here doesn't exempt you from other states' rules (economic nexus is about where your customers are), and Florida's lack of a personal income tax has no bearing on sales tax — you collect Florida sales tax from dollar one on in-state sales, at 6% plus your county's surtax. Full home-state details live in our Florida sales tax business guide.

Do marketplace sales count — and who collects on them?

Every state with a statewide sales tax now has a marketplace facilitator law: Amazon, Etsy, eBay, Walmart, TikTok Shop and the rest must collect and remit tax on sales made through their platforms. Three practical consequences:

• You don't collect on marketplace orders. The platform does. This removes most of the compliance burden for marketplace-only sellers.
• Marketplace sales usually still count toward your nexus threshold. In many states, $80,000 through Amazon plus $30,000 through your Shopify store means you've crossed $100,000 — and you must register and collect on the direct sales yourself.
• Registration may still be required even with zero direct sales in some states, though many now waive filing for marketplace-only sellers. State-by-state answers vary; our Amazon seller compliance guide covers the FBA wrinkles, including the inventory-nexus question.

When do you have to register — and what if you collect without registering?

The sequence matters and sellers regularly get it backwards:

1. Monitor sales by state (your platform's reports or tax software do this) and flag states where you're approaching a threshold.
2. Register before you collect. Collecting tax without a permit is illegal in most states — you're holding state money without authority. Once you cross a threshold, states typically require registration by the next transaction or within a short grace window (Florida, for example, expects registration once prior-year taxable sales exceed $100,000).
3. Configure collection in your cart — destination-based rates, product taxability codes (clothing, food, and digital goods have special rules in various states), and shipping taxability, which differs by state.
4. File on the schedule the state assigns — monthly, quarterly, or annually, including zero-dollar returns. Skipping a "nothing due" filing still generates penalty notices.

One bright spot: the Streamlined Sales Tax program lets you register in its 24 member states through a single application, with free certified software available for qualifying remote sellers.

What if you've had nexus for years and never collected?

This is the scary one, and it's more fixable than it feels. Uncollected tax doesn't disappear — the state can assess you for tax your customers never paid, plus penalties (often 25%+ of the tax) and interest, with no statute of limitations running if you never filed. But states want sellers in the system, so nearly all offer voluntary disclosure agreements (VDAs): come forward before they find you, and the state typically limits the lookback to 3–4 years and waives most or all penalties.

A hedged example: an apparel brand selling on Shopify discovers it crossed $100,000 in Georgia and North Carolina back in 2023 and never registered. Roughly $180,000 of untaxed sales across the two states at ~7% is about $12,600 of tax exposure before penalties. Through VDAs, the brand registers, pays the limited-lookback tax and interest, sees penalties largely waived, and starts collecting properly — turning an open-ended liability into a known, financed number. Every state's VDA terms differ; the "come forward first" principle is universal.

Sellers usually land on this page at exactly that moment — mid-cleanup, notice in hand, or growth outpacing the spreadsheet. Problems come here to get solved. Our sales tax team runs nexus studies, registrations, and VDAs, and keeps the filings running after.

How do you stay compliant without it eating your week?

• Automate rate calculation and filing once you're in more than two or three states — tax engines (TaxJar, Avalara, and platform-native tools) handle rates across thousands of jurisdictions better than any human.
• Re-check thresholds twice a year. Growth creates new nexus; so do new warehouse locations and hires.
• Keep exemption/resale certificates for any wholesale orders, organized by customer.
• Calendar every state's frequency and set autopay where available — most penalties we see are for late filing, not wrong math.

E-commerce nexus is one half of the puzzle; if you also sell services, have employees in other states, or attend trade shows, the broader rules are in our companion guide to multi-state sales tax compliance.

FAQ

Do I charge my state's rate or the customer's?

For interstate e-commerce, almost always the customer's — destination-based sourcing at the rate for their delivery address, including local add-ons. Your software should resolve this from the ZIP+4 or full address.

Is shipping taxable?

Depends on the state: some tax delivery charges whenever the goods are taxable, others exempt separately stated shipping. Configure it per state rather than guessing one way for everyone.

Do digital products and SaaS create nexus issues too?

Yes — economic thresholds apply to digital sales, and taxability varies more than for physical goods (some states tax downloads and SaaS, others don't). Sellers of digital goods should run the same threshold analysis with extra attention to what's taxable where.

What happens if I fall back below a threshold?

Generally you keep collecting while registered; many states let you cancel the registration after a full year (or more) below the threshold. Some apply "trailing nexus" for a period after activity stops. Check the specific state before switching anything off.

Does crossing a sales tax threshold mean I owe income tax there too?

Not automatically — income tax nexus runs on separate (and fuzzier) standards. But heavy sales into a state can raise income-tax questions as well, which is worth a conversation before it's worth a worry.

Reviewed by the WAYG tax team · Updated July 2026