SST vs marketplace facilitator laws

Marketplace facilitator laws and the Streamlined Sales Tax (SST) program are not alternatives, so there’s nothing to choose between. A marketplace facilitator law is one state’s rule about who collects tax on a sale made through a marketplace. The program is 24 states agreeing on how sales tax is administered. The marketplace collects on its channel where that state’s law puts the duty there, you collect on your direct channel, and you are usually still filing a return in that state showing both.

If you sell through Amazon or Walmart and on your own site, both of these apply to you at once, in every state where you have nexus.

What does a marketplace facilitator law actually do?

It moves the collection duty from the seller to the platform for sales made through that platform.

The practical test for whether a platform is a facilitator, in the states’ own framing, is the money: a facilitator is a business that operates a marketplace and takes the buyer’s payment, then passes some or all of it to the third-party seller. Where the platform takes the payment, the sale is usually facilitated. Where the buyer pays you directly, it usually falls back to you.

These are state laws, enacted state by state, with thresholds and details that differ. They aren’t part of the Streamlined Agreement.

Does the SST program change who collects on a marketplace sale?

No. Each state’s own marketplace facilitator law decides that, and it decides the same way whether or not the state is a member.

This is the whole reason the question is malformed. One is a rule about who collects. The other is an agreement about how administration works for whoever is collecting. Put a member state and a non-member state side by side and they describe the same mechanic in nearly the same words: Washington, a full member, and California, which is not a member, both make the facilitator the collector, both keep the seller filing its own return, and both count facilitated sales toward the seller’s own threshold. Program membership shows up nowhere in that shape.

If the marketplace already remitted, what do you report?

Usually still a return, and this is where sellers get caught.

A marketplace remitting the tax generally leaves your own filing duty in place in a state you are registered in. Washington’s Department of Revenue tells a marketplace seller to report its gross sales and then deduct the facilitated ones, so the return shows the full picture and the tax isn’t paid twice. California asks for total sales on the same logic. The mechanics differ by state, and a few handle it differently again.

Two things follow. The return stays yours even where a platform collected, and an empty-looking period is still a period. That sits with your ongoing obligations.

Treat the marketplace as having handled the collection, not as having handled your compliance.

Do marketplace sales count toward your thresholds?

In some states yes, and that surprises people who assume the platform absorbed the whole question.

Whether marketplace-facilitated sales count toward a state’s economic nexus threshold varies by state. Some include them, some exclude them, some count them for one test and not another. The consequence is that a seller doing most of its volume through marketplaces can still cross a threshold and acquire an obligation on its direct channel, which is a real outcome and not an edge case. How thresholds interact with the program is on SST and economic nexus.

For the program itself, marketplace sales carry no special status. Nothing in the shared registration system or the uniform return treats them as a separate category. They also have no bearing on whether you qualify as a CSP-compensated seller: that test runs on premises, property and payroll in the state, not on which channel your sales came through. See the CSP-compensated seller test.

What does a mixed-channel seller actually have to do?

Checklist: what a seller selling on its own site and through marketplaces has to do in a given state, in this order. Checked September 1, 2026.

1. Work out where you have nexus, counting marketplace sales the way each state counts them.
2. Register where you are required to, through the shared system for member states and on each state’s own form elsewhere. See how to register.
3. Collect on your direct channel in every state where you are registered.
4. Let the marketplace collect on its channel where that state’s law puts the duty there.
5. File in every state you registered in, every period, showing marketplace sales the way that state requires.
6. Keep the two channels separable in your records, because the return asks you to distinguish them and an audit will.

Step six is the one that gets skipped and the one that costs the most later.

How providers handle marketplace orders is a commercial term, not a program rule

The six certified providers do not publish a common position on this. TaxCloud states that it does not file marketplace facilitator orders, on the grounds that the marketplace already remits to the state, while still counting those orders in your nexus tracking. Sovos, Avior and AccurateTax publish about platform connectors rather than about how marketplace orders are filed, so their treatment is a question to ask rather than a published position. That is each provider’s own arrangement with you.

Nothing in the Agreement decides it, so do not read a provider’s practice as the program’s rule, and do not assume two providers handle it the same way. Ask what your provider does with marketplace orders before you rely on any of it. The six are compared at the provider directory.

What the program will not do for you here

Nothing in the Streamlined program helps with marketplace facilitator questions, and that is worth saying plainly rather than implying otherwise.

• Who collects is state law, decided outside the Agreement.
• The treatment stays per state. The Governing Board publishes per-state charts on marketplace facilitator rules precisely because the answers differ, and those charts carry the Board’s own note that each state’s own laws govern.
• Your return survives it. A platform collecting is a platform collecting, and the filing stays with you.
• The other 21 states run their own, many of them with marketplace facilitator laws of their own. See what changes on either side of the membership line.

The uniform definitions, the shared registration, and the one-return rule are all real, and all of them stop short of this. Marketplace facilitator compliance is a per-state question you answer per state, and enrolling changes only the paperwork around the return it lands on.