Multi-Channel Ecom: How Your Direct Shopify Sales and Amazon/Etsy Revenue Combine Toward the $100K Nexus Threshold in Most States

The Post-Wayfair Baseline: $100K or 200 Transactions

Since the 2018 South Dakota v. Wayfair decision, most U.S. states have adopted economic nexus thresholds that require remote sellers to collect and remit sales tax once they exceed a revenue or transaction volume in the state. The most common threshold is $100,000 in gross revenue or 200 transactions during a lookback period (typically the prior calendar year or a rolling 12-month window). Some states — including California ($500,000), Texas ($500,000), and New York ($500,000 plus 100 transactions) — set higher bars. A few states have dropped the transaction prong entirely, leaving only a revenue test.

For single-channel sellers, the math is straightforward: add up your sales into the state and compare against the threshold. But for multi-channel retailers selling through a mix of direct storefronts and third-party marketplaces, the question becomes: which sales count?

The Majority Rule: Marketplace-Facilitated Sales Are Excluded

The critical principle that most multi-channel sellers miss: in the majority of states with marketplace facilitator laws, sales made through a qualifying marketplace facilitator are excluded from the individual seller's economic nexus threshold calculation. The logic is simple — if Amazon is already collecting and remitting tax on your facilitated sales in that state, those sales should not also trigger a separate collection obligation for you.

This means that for threshold purposes, your revenue in a state equals your non-facilitated (direct-channel) sales only. Your Shopify storefront revenue counts. Your wholesale orders count. Custom orders placed through your own website count. But the $65,000 that Amazon processed on your behalf? In most states, that is excluded from your threshold math because Amazon already handled the tax.

The practical impact is significant. A seller with $155,000 in total revenue in a state might assume they have blown past the $100,000 threshold. But if $85,000 of that revenue came through Amazon and Etsy as facilitated sales, only $70,000 counts — and the seller has no economic nexus obligation in that state.

States That Exclude Marketplace-Facilitated Sales from the Threshold

The following table summarizes how the most common ecommerce states treat marketplace-facilitated sales in the nexus threshold calculation. The majority follow the exclusion rule, but the exceptions matter.

The pattern is clear: states want marketplace facilitators to bear the collection burden, and they generally do not double-count sales that the facilitator is already handling. But Washington and Minnesota take the position that the seller's total economic activity in the state determines nexus — regardless of who collects the tax. If you sell heavily into either state across multiple channels, your total gross revenue (direct plus facilitated) applies to the threshold.

Why Washington and Minnesota Diverge

Washington was the first state to enact a comprehensive marketplace facilitator law and takes the broadest view of seller nexus. Washington's position is that economic nexus measures the seller's economic presence in the state — and all sales into Washington contribute to that presence, whether or not a facilitator collected tax. Practically, this means a seller with $40K in Shopify sales and $70K in Amazon sales in Washington has $110K counting toward the threshold and has nexus, even though Amazon collected tax on the $70K.

Minnesota follows a similar approach. The state's economic nexus statute measures "retail sales" made into Minnesota without distinguishing between facilitated and non-facilitated channels. A multi-channel seller must add up every dollar of revenue shipped to Minnesota customers, regardless of platform.

The practical consequence: sellers with significant Amazon or Etsy volume in Washington or Minnesota may have nexus obligations they do not have in other states at the same revenue levels. If you are a multi-channel retailer with $80K–$120K in combined sales in these states, check your direct-channel-only totals and your combined totals.

Worked Example: $70K Shopify + $65K Amazon + $20K Etsy in One State

Consider a home goods retailer based in Oregon (no state sales tax) selling nationally through three channels. In a single target state, their trailing 12-month revenue breaks down as follows:

The difference is stark. In 45+ states, this seller has no nexus obligation. In Washington and Minnesota, they do. A seller tracking only gross revenue across all channels would incorrectly conclude they have nexus everywhere at $155K — or, worse, a seller ignoring marketplace sales entirely might miss the Washington and Minnesota obligations.

The Marketplace Facilitator Nuance: Coverage Gaps Still Exist

Even in majority-rule states where facilitated sales are excluded from the threshold, marketplace facilitator coverage is not always complete. Several situations can leave you exposed:

• Platforms that are not registered facilitators in every state. Smaller marketplaces — Faire, Poshmark, or niche vertical platforms — may not qualify as marketplace facilitators in all states. If the platform is not registered, those sales count as your direct sales for threshold purposes.
• States with marketplace facilitator coverage gaps. Some states define "marketplace facilitator" narrowly, excluding platforms that merely list products without processing payment. Verify that each platform you sell through meets the facilitator definition in each state.
• Non-marketplace sales through a platform. If you use Shopify as your storefront but process orders through Shopify Payments, Shopify is not acting as a marketplace facilitator — it is a payment processor. The distinction matters: payment processors do not shift the tax collection obligation. All Shopify direct sales are your responsibility.
• B2B or wholesale orders placed outside the marketplace. If an Amazon customer contacts you directly for a bulk order and you invoice them outside Amazon, that is a direct sale — even if the relationship originated on Amazon.

The takeaway: "I sell on Amazon so Amazon handles it" is only true for the transactions Amazon actually facilitates. Everything else is on you.

Physical Nexus Complicates the Picture

Economic nexus thresholds are only one piece of the puzzle. If you use Amazon FBA, your inventory stored in Amazon warehouses creates physical nexus in every state where that inventory sits — regardless of your revenue in that state. Physical nexus triggers a collection obligation on your direct-channel sales in that state even if you are below the economic nexus threshold.

This creates a common trap for multi-channel sellers: Amazon FBA establishes physical nexus in a state, the marketplace facilitator law covers your Amazon sales, but your $30K in Shopify direct sales to that state are now taxable because you have physical nexus through inventory. Many sellers miss this because they assume the marketplace facilitator law covers all their obligations — it only covers the facilitated transactions.

Quarterly Self-Audit Spreadsheet for Multi-Channel Sellers

Tracking nexus exposure across 10 target states and three or more sales channels requires a structured approach. Here is the framework for a quarterly self-audit spreadsheet:

Canadian Cross-Border Sellers: Additional Considerations

Canadian sellers operating on Amazon.com, Shopify, and Etsy face the same multi-channel nexus rules as domestic U.S. sellers. Economic nexus is measured by sales into a state, not the seller's country of origin. But several practical issues are unique to cross-border sellers:

• Amazon.ca revenue does not count toward U.S. state thresholds. Only sales shipped to addresses within the state count. Sales to Canadian customers through Amazon.ca are entirely outside U.S. state nexus calculations.
• Currency conversion matters. U.S. thresholds are in USD. If you invoice in CAD through your Shopify store, convert at the transaction-date exchange rate. The transaction counting rules for recurring charges apply to each converted amount.
• GST/HST is entirely separate. Canadian goods and services tax obligations do not interact with or offset U.S. state sales tax. You may owe both simultaneously.
• Amazon FBA in the U.S. creates physical nexus. If you ship inventory to Amazon U.S. fulfillment centers, you have physical nexus in every state where that inventory is stored — and your direct Shopify sales into those states become taxable regardless of whether you have crossed the economic nexus threshold.

Decision Tree: Do Your Multi-Channel Sales Create Nexus?

For each state where you have customers, walk through this sequence:

1. Do you have physical nexus? (Inventory in FBA warehouses, employees, office, or property in the state.) If yes → you have nexus regardless of revenue. Register and collect on direct-channel sales. Stop here.
2. Does the state exclude marketplace-facilitated sales from the threshold? Check the table above. If yes → only your direct-channel (Shopify, website, wholesale) revenue counts. If no → add all channels together.
3. Does your countable revenue exceed the state threshold? Compare against $100K (or $500K for CA, TX, NY). If yes → you have economic nexus. Register and begin collecting on direct-channel sales.
4. Are you at 75% or above? If yes → set a calendar reminder to re-check next quarter. You may cross mid-period.
5. Are you well below threshold? No action needed for this state this quarter. Revisit next quarter.