Online sellers hit sales tax problems in a predictable order: one channel, then two, then a warehouse, then a letter. Here's how to stay ahead of it in every state you sell into.
How do you guys deal with sales tax in 15 states?
It's a question that shows up in ecommerce Facebook groups every week. Nobody plans to be registered in 15 states. You grow into it.
First you sell on Etsy and the marketplace handles tax. Then you open a Shopify store. Then you use a fulfillment network and your inventory ends up in warehouses in states you've never visited. Then you have a great holiday season, and suddenly you're over the line in places you weren't watching.
Here's how that path works, where it trips sellers up, and how to stay in front of it.
Do I need to collect sales tax when selling to other states?
Only where you have nexus. For online sellers, there are two triggers.
Economic nexus: your sales into a state cross its threshold, often $100,000 in the current or prior calendar year. Every state with a sales tax has one of these laws now, a result of the 2018 Wayfair decision (Avalara, 2026). Some states also count transactions; 15 states plus D.C. and Puerto Rico still do (Avalara, 2026).
Physical nexus: inventory, staff or property in the state. For sellers using third-party fulfillment, inventory location is the one that surprises people most.
Etsy sellers: do you collect sales tax, or does Etsy?
On Etsy, Amazon and most major marketplaces, the marketplace generally collects and remits tax on your marketplace orders under marketplace facilitator laws. If that's your only channel, your sales tax workload is light.
Two catches. First, your own website is still your responsibility. Second, some states count marketplace sales toward your economic nexus threshold even though the marketplace collected the tax. So a seller doing $70,000 on Etsy and $40,000 on Shopify into one state may have crossed $100,000 there, depending on that state's rules.
Track all channels together, then apply each state's rule about what counts. A single combined view by state is the one report most multi-channel sellers are missing, because each platform only reports its own sales.
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Download the free Blueprint →Why Q4 is when sellers cross the line
Holiday season compresses a big share of annual orders into a few weeks. For low-ticket products, that's where transaction tests bite: one sales tax firm told the Senate that a third of its clients with under $50,000 in sales into a state had to register solely because they crossed 200 transactions (Yetter testimony via Avalara, 2026).
And timing matters. In approximately 12 states and D.C., you're expected to start collecting as soon as you cross (Avalara, 2026). Cross on December 5th and the obligation can start right then, while you're busiest and least likely to notice.
The fix is to watch your pace by state in October and November, not to look back in January.
Shopify isn't collecting sales tax from out-of-state customers
This is the most common ecommerce sales tax mistake, and it's a setup gap, not a bug. Shopify collects in states where you've added a registration. If you crossed a threshold but haven't registered and added it, checkout won't charge tax there.
How to set up sales tax in Shopify, in short: register with the state, add the registration in your tax settings, and assign product tax categories for anything with special treatment, like clothing or digital goods. Check a test order to that state before you rely on it.
Do the same review for every other channel you sell through directly, like wholesale or a second storefront. Each one needs its own tax settings, and they don't share them automatically. Recheck them every time you add a state registration.
Wholesale, exemptions and the paperwork trap
Many ecommerce brands add wholesale. Sales to resellers are usually exempt from sales tax, but only if you collect and keep a valid resale or exemption certificate from the buyer.
Without the certificate, an auditor can treat that sale as taxable and bill you. It's one of the easiest audit findings to avoid and one of the most common to miss. Keep certificates organized by customer and state, and check expiration dates.
Records matter in general: 28% of small businesses say they've been audited or received an IRS notice (OnPay, 2019). State sales tax reviews come on top of that.
What it costs an online store to get this wrong
Uncollected tax comes from your margin. A store selling $180,000 a year into a state for two years after crossing nexus, at a combined rate around 8%, would owe about $28,800 before interest and penalties. Rates vary widely by location; that's illustration, not a quote.
Penalties and interest can add meaningfully on top, and you can't go back and charge those customers. Then there's time. 63% of early-stage owners say they waste at least one day a month on financial admin, and tax calculations are the top frustration at 54% (Tide, 2016). For a seller filing in a dozen states, the filing calendar alone is a part-time job.
Software helps, at a price. Our Blueprint estimate for sales tax software is about $130 a month for a typical 10-person company.
A simple system for multi-state sellers
- One sheet, all channels. Orders by ship-to state, dollars and count, marketplace and direct separated.
- Verified thresholds. Each state's sales test, transaction test and measurement period, with the date you checked.
- Monthly pace check. Percent of threshold and projected crossing date, especially in Q4.
- Inventory map. Which states your stock sits in, from your fulfillment reports.
- Filing calendar. Every registered state, frequency and due date, with zero returns included.
- Certificate folder. Exemption certificates by customer and state.
What owning the system looks like for a store
Picture the first of the month: "You're at 84% of Georgia's sales threshold and on pace to cross in the second week of December. Inventory showed up in a new state last month. Three returns due this month; worksheets attached."
That's a tracker built with your own AI, in your own accounts, reading your Shopify, Etsy and Amazon data. You still register and file, yourself or through your accountant. But you replace the subscription you'd otherwise pay for the watching, and the system is yours to keep, even after you cancel.
Questions owners ask
Do I need to collect sales tax from each state in the US?
No. Only in states where you have nexus, from crossing an economic threshold or having inventory, staff or property there. Five states have no statewide sales tax at all.
Does Amazon FBA inventory create nexus?
Inventory stored in a state is generally treated as physical presence, which can create nexus even if your sales there are small. Check your inventory reports by warehouse location.
How do I charge sales tax on out-of-state online orders?
Register in that state, then add the registration in your store's tax settings. Your platform calculates the right rate at checkout from there.
Is shipping taxable on online orders?
It depends on the state and sometimes on how shipping is listed on the invoice. Confirm the rule in each state where you're registered and set your store's tax settings to match.
What if I already crossed nexus and didn't collect?
Talk to a CPA before contacting the state. Many states offer voluntary disclosure programs that can limit penalties and lookback periods.
Own the system instead of renting it
Valuexus builds it inside your own accounts, usually within 24 hours, and it stays yours even if you cancel. $450 a month, locked for life; your first month is $225 with code WELCOME50. 7-day, 75% money-back guarantee.
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Sources
- Every state with a sales tax has an economic nexus law, following South Dakota v. Wayfair (June 21, 2018) — Avalara, 2026
- A transaction threshold still applies in 15 states, Puerto Rico and Washington, D.C.; 13 states never had one — Avalara, 2026
- A third of one sales tax firm's clients with under $50,000 in sales in a state had to register solely because they crossed 200 transactions — Diane Yetter Senate testimony, cited by Avalara, 2026
- In approximately 12 states and D.C., sellers must start collecting as soon as they cross a threshold — Avalara, 2026
- 28% of small businesses have been audited or received an IRS notice — OnPay Small Business Finance and HR Report, 2019
- 63% of early-stage owners say they waste at least one day a month on administrative financial tasks — Tide survey via Startups.co.uk, 2016
- Owners' top financial admin frustrations: tax calculations (54%), accounting (51%), tracking expenses (49%), juggling multiple apps (38%) — Tide survey via Startups.co.uk, 2016
Written by Hunter J. Schneider, founder of Valuexus. Get your free 173-point AI audit.