What it is

A marketplace seller is a third-party business that lists and sells its products through an online marketplace — Amazon, Walmart, Etsy, eBay, and similar platforms — rather than only through its own website. In sales tax terms, the seller is distinct from the marketplace facilitator, which is the platform that provides the storefront and processes the payment.

That distinction matters because of marketplace facilitator laws, now in effect in every state that collects sales tax. These laws shift the duty to collect and remit tax on platform sales from the individual seller to the facilitator. So when a customer buys your product on Amazon, Amazon — not you — calculates, collects, and remits the sales tax to the state. <!– src: https://www.taxjar.com/sales-tax/marketplace-facilitator-laws –>

Why it matters to a multi-state seller

It’s tempting to read “the platform collects for me” as “I have no sales tax obligations.” For most multi-state sellers, that’s wrong on three fronts, and each is a common audit finding.

First, your marketplace sales usually still count toward your economic nexus threshold. Second, you may still have to register and file in states where you’re considered to have nexus, even if every dollar of tax was collected by the platform — often as a zero return. Third, direct sales are entirely yours. The moment you sell off-platform — your own Shopify store, wholesale invoices, phone orders — no facilitator is collecting, and you must handle that tax yourself. A business that sells both ways carries both obligations at once.

Worked example

Imagine your brand sells in California through two channels over a year:

• Amazon (marketplace): $450,000 in sales. Amazon collects and remits the California tax on all of it.
• Your own website (direct): $80,000 in sales. No facilitator involved.

You might assume only the $80,000 of direct sales matters. But California includes marketplace sales in the seller’s own threshold calculation, so your nexus math is $450,000 + $80,000 = $530,000 — over California’s $500,000 threshold. <!– src: https://www.galvix.com/sales-tax-nexus/california/ –> That means you have economic nexus, you must register, and you must collect and remit tax on the $80,000 of direct sales yourself. Amazon’s collection covers the marketplace portion, but it doesn’t cover your website — and it didn’t keep you under the threshold.

Had your direct sales been $0, you’d still cross the threshold on facilitated sales alone, and some states would then expect a registration and a zero return confirming the platform handled collection.

State-level nuance

The mechanics vary by state, and three questions drive the differences:

Because some states allow exclusive marketplace sellers to cancel a registration without penalty while others still want a return, you should confirm each state’s rule before either registering or closing an account. <!– src: https://www.streamlinedsalestax.org/for-businesses/marketplace-facilitator –>

How this connects to staying compliant

For a marketplace seller, compliance is about drawing the line between what the platform covers and what it doesn’t. Map your sales by state and by channel. In each state, ask: do my combined sales cross the economic nexus threshold? If so, do I have direct (off-platform) sales that I must collect on? And does the state require me to register and file even where the facilitator collected everything?

Get those three answers right per state and you register only where you must, file the returns that are genuinely required, and avoid the two opposite errors — over-collecting tax the platform already handled, and ignoring direct-sale obligations the platform never touched.

Sources: TaxJar — Marketplace facilitator laws, explained: https://www.taxjar.com/sales-tax/marketplace-facilitator-laws Streamlined Sales Tax — Marketplace Facilitator State Guidance: https://www.streamlinedsalestax.org/for-businesses/marketplace-facilitator Galvix — Sales Tax Nexus in California 2026 (marketplace sales count toward threshold): https://www.galvix.com/sales-tax-nexus/california/