Marketplace facilitator tax laws make the online platform hosting a sale, rather than the individual third-party seller, responsible for charging sales tax at checkout, collecting it from the buyer, and sending it to the state. Every state that imposes a sales tax now has one of these laws on the books, which is why Amazon, eBay, Etsy, Walmart Marketplace, and similar sites handle sales tax on your behalf when you sell through them. The rules trace back to the U.S. Supreme Court’s 2018 decision in South Dakota v. Wayfair, which allowed states to tax remote sales based on economic activity alone, without requiring the seller to be physically present in the state.1Supreme Court of the United States. South Dakota v. Wayfair, Inc. What each state expects, and what still falls on the seller, differs enough to be worth walking through.
Which Platforms Count as Marketplace Facilitators
A business becomes a marketplace facilitator when it does more than list products. The trigger is active involvement in completing the sale. If the platform takes orders, processes payments, and connects a buyer with a third-party seller’s inventory, it meets the definition in virtually every state. A site that only advertises products or links out to a seller’s own checkout generally does not qualify, because it never touches the money or controls the transaction.
Most state definitions require two elements together: an electronic marketplace where products are listed, and integrated payment processing that routes funds between buyer and seller. Platforms that also arrange shipping, manage returns, or set delivery terms fit the definition even more clearly. Amazon, eBay, Etsy, Walmart Marketplace, TikTok Shop, and Shopify’s Shop app all qualify. So can smaller platforms that process payments and facilitate delivery for third-party sellers, once they hit a state’s economic thresholds.
When the Collection Duty Kicks In
Before Wayfair, a state could only require a business to collect sales tax if that business had a physical presence there. The Supreme Court replaced that rule with an economic-activity standard.1Supreme Court of the United States. South Dakota v. Wayfair, Inc. The South Dakota law upheld in the case set the benchmark: $100,000 in gross sales or 200 separate transactions delivered into the state in a calendar year.
Most states adopted that same $100,000 threshold, and it remains the most common baseline. A handful set higher bars. The calculation aggregates everything moving through the platform: the facilitator’s own direct sales plus all sales made by third-party sellers. Once the total crosses the line, the facilitator has to register and begin collecting tax on future orders shipped into that state.
The Transaction Count Is Fading
The 200-transaction prong is disappearing. As of mid-2025, at least 15 states have dropped it and kept only the dollar threshold, including California, Colorado, Massachusetts, North Carolina, Washington, and Wisconsin. Illinois is set to drop its transaction threshold effective January 1, 2026. The reasoning: a seller running 200 small transactions may generate very little revenue, and states have concluded that the compliance burden isn’t worth the tax collected.
What Counts Toward the Threshold
Whether exempt and non-taxable sales count toward the $100,000 figure depends on the state. Some measure gross sales, which sweeps in taxable sales, exempt sales, and even sales for resale. Others look only at retail sales, excluding wholesale. A smaller group counts only taxable sales, stripping out exempt transactions. This choice can move the date you cross into nexus by months, so getting the measurement right for each state matters.
How the Platform Collects the Tax
Tax is calculated at checkout using the buyer’s shipping address. This destination-based approach means the platform has to apply the correct combination of state, county, city, and special district rates for every delivery location. An order shipped to a customer in a city with an added transit tax carries a different rate than one shipped across the county line. The platform collects that amount as part of the purchase price and holds it until remittance.
A small number of states use origin-based sourcing for in-state sales, keying the rate to the seller’s location instead of the buyer’s. For remote sales crossing state lines, though, destination sourcing is nearly universal. Facilitators operating nationally maintain rate databases accurate to the address level, which is why many rely on automated tax calculation software.
Handling Exempt Buyers
Tax-exempt buyers, such as resellers purchasing inventory or nonprofits buying supplies, still need to provide valid exemption certificates to avoid being charged. Some large platforms run dedicated programs for this. Amazon’s Tax Exemption Program lets qualified buyers upload certificates and suppresses tax on eligible orders automatically. On platforms without a built-in tool, someone still has to collect and store those certificates, because if an audit turns up exempt sales with no documentation, the tax may end up owed anyway. Who absorbs that risk varies by state and by the seller agreement.
What Third-Party Sellers Still Owe
The facilitator’s collection duty covers only sales made through the marketplace. If you also sell through your own website, at craft fairs, or through any other channel, those sales remain your responsibility. You have to determine on your own whether you have economic or physical nexus in each state and collect tax on direct sales accordingly.2Streamlined Sales Tax Governing Board. Marketplace Seller State Guidance
Inventory in a Warehouse Can Create Nexus
Sellers using fulfillment programs like Fulfillment by Amazon should know that storing inventory in a state’s warehouse can create physical presence nexus, even if you have never set foot there. More than 20 states explicitly treat marketplace inventory as a physical presence trigger for the seller. In those states, if you also make direct-to-consumer sales, you may need to register and collect tax on those sales regardless of whether you meet the economic threshold. A few states, including Arizona and New York, generally don’t treat third-party warehouse inventory as creating nexus for the seller, provided the seller doesn’t control the inventory and it’s used only to fulfill marketplace orders.
Income Tax Is Separate
Marketplace facilitator laws cover sales tax only. They don’t touch your obligation to report income or pay income tax on your earnings. Facilitators generally issue 1099-K forms to sellers whose transaction volumes hit the federal reporting threshold, so the IRS will see your sales revenue whether or not you report it.
Registering and Filing
A facilitator must register for a sales tax permit in every state where it meets the economic threshold. Registration usually asks for the company’s Federal Employer Identification Number, legal business name, officer information, estimated monthly sales, and the number of third-party sellers on the platform. Most states handle this through their Department of Revenue website, and registration is typically free or costs only a few dollars.
Registering individually in dozens of states is tedious, so the Streamlined Sales Tax Registration System offers a single online application covering 24 participating states.3Streamlined Sales Tax Governing Board. Sales Tax Registration SSTRS For states outside that group, you still register directly with each state’s tax authority. Platforms that want to outsource compliance can also contract with a Certified Service Provider under the Streamlined Sales Tax Agreement to handle calculation, filing, and remittance.4Streamlined Sales Tax Governing Board. Certified Service Providers
Filing frequency depends on volume. States generally assign monthly filing to high-volume facilitators, quarterly to mid-range filers, and annual to those with minimal liability. Frequency can change as your sales grow, and most states will notify you if they move you to a more frequent schedule. Returns are submitted through the state’s online tax portal, reporting total gross sales, total taxable sales, and tax collected for the period. Many states offer a return form designed for marketplace facilitators so that platform sales and third-party seller sales are categorized separately. Payment is usually made by ACH debit or credit, and some states require electronic payment once your liability crosses a certain level.
Errors, Relief, and Penalties
Applying the right rate to millions of transactions across constantly shifting jurisdictions is hard, and most states recognize that. The most common form of liability relief applies when the mistake came from inaccurate information the seller provided, such as a wrong product category. If the facilitator can show a reasonable effort to get accurate information and the error wasn’t its fault, many states waive the tax deficiency along with penalties and interest. The protection has limits: it usually doesn’t cover sourcing errors the facilitator should have caught, it typically requires the facilitator and seller to be unrelated, and some states cap the relief at a percentage of annual tax due. Where the facilitator is excused, the seller may end up liable for the shortfall.
A few states also allow facilitators and sellers to enter written agreements shifting collection duty back to the seller. Nevada, Minnesota, New Jersey, and Tennessee have some version of this opt-out, though the conditions are strict. Tennessee, for example, only allows it when the seller is registered in the state and has more than $1 billion in annual gross sales nationwide.5Streamlined Sales Tax Governing Board. Marketplace Facilitator State Guidance
When a facilitator fails to register, collect, or remit, the penalty structure looks like any other sales tax collector’s. Late filing penalties generally run between 2% and 10% of unpaid tax, and interest accrues from the original due date. The bigger exposure is back tax. If a facilitator should have been collecting and wasn’t, the state can assess the full uncollected amount for the entire non-compliance period. The standard three-year statute of limitations for assessment stretches to six years or longer when no returns were filed at all. Most serious trouble comes not from filing a return late but from not realizing there was a filing obligation to begin with.
Records and Audits
Every sale needs a paper trail. Facilitators should keep itemized transaction logs showing the date, dollar amount, buyer’s shipping address, tax rate applied, and tax collected, with the facilitator’s own sales clearly separated from third-party seller sales. Exemption certificates for non-taxable sales, bank statements, and gross receipts round out what an auditor will ask for.
Retention periods vary by state but generally fall in the three-to-seven-year range.6Internal Revenue Service. Recordkeeping Keeping records for the full seven years is the safer approach, especially because the look-back window expands when returns weren’t filed. If you can’t produce records on request, the state will estimate what you owe from whatever data it has, and the estimates rarely favor the taxpayer. Audits of marketplace facilitators tend to focus on three recurring issues: whether the correct rate was applied to each destination address, whether exempt sales have valid supporting certificates, and whether third-party seller transactions were properly reflected on returns. Organized, searchable digital records indexed by jurisdiction make those reviews far easier than reconstructing transaction histories years later.