What is the Wayfair ruling, and what did it change for online sellers?

The Wayfair ruling is the 2018 Supreme Court decision that changed how sales tax works for online businesses. Before it, you only had to collect sales tax in states where you had a physical presence: an office, an employee, a warehouse. After it, states can require you to collect based purely on how much you sell to customers there.

It’s the single biggest change to sales tax law in 30 years, and it’s the reason ecommerce sellers today face compliance obligations in states they’ve never set foot in.

The law before Wayfair

For decades, the rule for sales tax collection came from a 1992 Supreme Court case called Quill Corp. v. North Dakota. The Quill decision held that a state could only require a business to collect its sales tax if that business had physical presence in the state: an office, a store, an employee, or some other tangible connection.

For catalog and mail-order businesses in 1992, this was workable. For ecommerce in the 2010s, it had become a massive loophole. Online retailers were shipping billions of dollars of goods to customers in states where they had no physical presence, and collecting no sales tax. States were losing an estimated $8–33 billion in uncollected tax annually.

The biggest online retailers (Amazon, Wayfair, Overstock) had deliberately structured their operations to minimize physical presence and avoid collection obligations. A retailer with $1 billion in California sales but no California warehouse, employees, or offices didn’t have to collect California sales tax.

The case itself

South Dakota grew frustrated with the revenue loss and passed a law in 2016 requiring out-of-state sellers to collect sales tax once they crossed $100,000 in sales or 200 transactions into South Dakota in a year. The law was explicitly designed to challenge the Quill decision.

Wayfair, Overstock, and Newegg sued, arguing the Quill physical presence rule made the South Dakota law unconstitutional. South Dakota argued that Quill was outdated and should be overturned.

On June 21, 2018, the Supreme Court agreed with South Dakota in a 5–4 decision. The Court held that requiring physical presence was an “artificial” standard that made no sense in the modern economy. States could now require collection based on economic activity: the volume of sales into the state, rather than physical presence.

The specific South Dakota threshold ($100,000 in sales or 200 transactions) was mentioned by the Court as an example of a “reasonable” threshold that wouldn’t impose undue burden on small sellers. That framing influenced what every state subsequently enacted.

What changed immediately

The ruling didn’t impose any collection requirement directly, it simply said states could require it. What followed was a rapid wave of state legislation.

By 2019, the vast majority of states had enacted economic nexus laws. By 2020, every state with a general sales tax had one in place. The standard threshold most states adopted: $100,000 in annual sales, often with an additional 200-transaction test (which many states have since dropped).

For sellers, the practical change was abrupt:

What it means for you today

Every ecommerce seller operating in 2026 is operating under Wayfair rules. The relevant questions are now:

Have you crossed the threshold in any states? For most growing ecommerce brands, the answer is yes, often in more states than they realize. The $100,000 threshold is reached quickly once a brand has national distribution. See What are the economic nexus thresholds by state? for the full state-by-state breakdown.

Are you collecting in those states? Many sellers who have crossed thresholds haven’t registered and aren’t collecting. This creates retroactive liability, not just for uncollected tax but for penalties and interest. The longer the gap, the larger the exposure.

Do you know when you crossed? The collection obligation begins from the date you cross the threshold, not from the date you register. Sellers who registered late may have a gap period of uncollected tax that needs to be resolved.

The sellers Wayfair most affected

Rapidly growing DTC brands. A brand that crossed $100K in Michigan or Wisconsin as it scaled didn’t know it had a Michigan or Wisconsin problem until a nexus questionnaire or penalty notice arrived.

Amazon-only sellers. Before Wayfair, Amazon’s collection handled most of the exposure. After Wayfair, the threshold question matters even for Amazon sellers, crossing $100K in sales to a state creates an obligation for non-Amazon channels regardless of what Amazon collects.

Shopify brands without automation. Shopify Tax and manual rate configurations weren’t built for 30-state compliance. Sellers who outgrew those tools sometimes found themselves with a multi-state gap.

What Wayfair didn’t change

Wayfair didn’t change anything about physical nexus. If you have an employee, a warehouse, FBA inventory, or any other physical presence in a state, you’ve always had a collection obligation there, that rule was never dependent on Quill and isn’t affected by Wayfair.

Wayfair also didn’t affect the five states with no general sales tax: Alaska, Delaware, Montana, New Hampshire, and Oregon. Those states have no economic nexus law because they have no sales tax to collect.