In most cases you pay sales tax on online purchases in the US, just as you would buying the same item in a physical store. Since the 2018 Supreme Court decision in South Dakota v. Wayfair, Inc., states can require online retailers to collect sales tax based on economic activity alone, even without a physical store or warehouse in that state. The exceptions are purchases from very small sellers who haven't crossed a state's sales threshold, purchases from states with no sales tax at all, and certain tax-exempt product categories. In this guide, we'll break down exactly how online sales tax works, why some purchases go untaxed, and what online sellers need to know about their own collection obligations.
Why Do You Pay Sales Tax on Online Purchases?
For most of the internet's early history, online retailers only had to collect sales tax in states where they had a physical presence — a store, warehouse, or office. This meant huge online retailers without local operations in your state could sell to you tax-free, while local brick-and-mortar competitors were stuck charging tax on every sale.
That changed permanently with South Dakota v. Wayfair, Inc. in 2018. The Supreme Court ruled that states could require out-of-state sellers to collect sales tax based on economic activity — how much they sell into a state — rather than requiring physical presence. This concept is called economic nexus, and it's the reason most online purchases today include sales tax, regardless of where the retailer is physically located.
Economic Nexus vs Physical Nexus: What's the Difference?
Understanding these two terms explains almost everything about when online sales tax applies.
Physical nexus means a business has a tangible presence in a state — a store, office, warehouse, or even inventory stored in a third-party fulfillment center (including Amazon FBA warehouses). Physical nexus has always triggered a sales tax collection obligation, long before the Wayfair decision.
Economic nexus means a business has crossed a state-specific sales or transaction threshold, even with zero physical presence there. Since Wayfair, nearly all US states with a sales tax have adopted economic nexus laws, meaning a seller can owe tax collection obligations purely based on sales volume into a state.
What Are the Economic Nexus Thresholds by State?
Thresholds vary meaningfully by state, though most cluster around a common pattern:
- Most states: $100,000 in annual sales into the state (some also include a 200-transaction threshold as an alternative trigger)
- California and Texas: $500,000 in annual sales, with no transaction-count threshold
- New York: $500,000 in sales and more than 100 separate transactions — both conditions must be met
Once a seller crosses a state's threshold, they generally must register and begin collecting sales tax starting immediately or in the following reporting period. This obligation isn't retroactive — sellers only owe tax collection on sales made after crossing the threshold, not sales made before.
If you want to understand exactly how these varying rates affect your actual purchase price by location, our free US Sales Tax Calculator by ZIP Code breaks this down instantly based on the specific address.
Comparison Table: In-Store vs Online Purchase Sales Tax
In-Store vs Online Purchase: Sales Tax Comparison
Tax Basis — In-Store: Store's physical location | Online: Buyer's shipping address (usually)
Who Collects — In-Store: The retailer directly | Online: The retailer or marketplace facilitator
🔗 Nexus Requirement — In-Store: Automatic (physical location) | Online: Economic or physical nexus required
Rate Applied — In-Store: Local rate where store is located | Online: Often destination-based (buyer's location)
Small Seller Exemption — In-Store: Rare | Online: Common, until nexus threshold is crossed
Why Do Some Online Stores Not Charge Sales Tax?
There are several legitimate reasons a specific online purchase might not include sales tax:
- The seller hasn't crossed economic nexus in your state — Small or newer online businesses may simply not have enough sales volume into your specific state yet to trigger a collection requirement.
- You're purchasing from a state with no sales tax — If the item ships from (and you're located in) a no-sales-tax state, no state-level sales tax applies at all.
- The product category is tax-exempt — Many states exempt specific categories like groceries, prescription medications, or certain clothing items from sales tax, online or off.
- International sellers without US nexus — Foreign sellers without economic or physical nexus in any US state generally aren't required to collect US sales tax, though this doesn't mean the purchase is definitively tax-free (see use tax below).
What Is Use Tax, and Do You Owe It If You Weren't Charged Sales Tax?
This is one of the most overlooked aspects of online shopping. Use tax is essentially the consumer-side counterpart to sales tax — if you purchase a taxable item and the seller didn't charge sales tax (because they lack nexus in your state), you technically still owe the equivalent amount directly to your state as use tax.
In practice, very few individual consumers actually track and pay use tax on personal purchases, and enforcement against individuals is rare. However, businesses are far more likely to face use tax scrutiny during audits, since untaxed business purchases from out-of-state vendors are a common audit target. If you run a business, understanding your use tax exposure alongside your sales tax collection obligations is worth taking seriously, not just assuming smaller purchases fly under the radar indefinitely.
Does Amazon Automatically Charge Sales Tax?
Yes, in virtually all cases. Under marketplace facilitator laws — now adopted by every state that imposes a sales tax, plus the District of Columbia — platforms like Amazon, Etsy, and Walmart Marketplace are required to calculate, collect, and remit sales tax on behalf of their third-party sellers automatically. This means individual sellers on these platforms generally don't need to handle sales tax collection themselves for marketplace sales, since the platform does it for them.
The important catch: marketplace sales can still count toward a seller's own economic nexus threshold in many states, even though the platform is handling collection. This means a seller could unknowingly cross a nexus threshold in a state based purely on marketplace sales volume, creating a separate registration obligation for any direct (non-marketplace) sales they make into that same state.
Are Digital Products Subject to Sales Tax?
This varies significantly by state, and it's an area with less consistency than physical goods. Some states tax digital products (ebooks, downloadable software, streaming subscriptions) identically to physical goods, while others exempt digital products entirely or apply different rules depending on the specific type of digital content. There's no uniform national standard here, making this one of the more state-specific areas of online sales tax to research if you're selling digital products specifically.
Destination-Based vs Origin-Based Sales Tax
Most states use destination-based sales tax for online purchases, meaning the tax rate applied is based on where the buyer receives the item — their shipping address — rather than where the seller is located. A smaller number of states use origin-based taxation for in-state sales, applying the seller's local rate instead, though this distinction typically matters more for sellers than for everyday online shoppers.
This is exactly why the same product from the same retailer might show different sales tax amounts depending on your shipping address — the system is calculating tax based on where you live, not where the warehouse sits.
Do Small Online Sellers Have to Collect Sales Tax?
Not automatically. Small sellers only need to begin collecting sales tax in a given state once they cross that state's specific economic nexus threshold — commonly $100,000 in annual sales, though $500,000 in states like California and Texas. This means many genuinely small online businesses, especially those just starting out, may have zero sales tax collection obligations in most states simply because they haven't reached meaningful sales volume there yet.
That said, nexus should be actively monitored, not assumed away — a seller experiencing rapid growth in a particular state can cross a threshold faster than expected, and the obligation to register and collect typically begins immediately once crossed.
How Do Online Sellers Know Which Sales Tax to Charge?
For sellers managing this themselves (outside of marketplace facilitator platforms), the process generally involves:
- Tracking sales by state to monitor progress toward each state's economic nexus threshold.
- Registering for a sales tax permit in any state where nexus has been established.
- Determining the correct rate based on destination address, which can include state, county, and city-level components.
- Collecting tax at checkout, typically automated through ecommerce platform tax settings (Shopify, WooCommerce) or dedicated tax automation software.
- Filing and remitting collected tax to each state according to that state's filing schedule.
If you're running an ecommerce business and want to understand your broader tax picture beyond just sales tax collection, our US Self-Employment Tax Calculator can help you understand your income tax obligations alongside sales tax responsibilities.
Which States Have No Sales Tax?
Five states currently charge no state-level sales tax at all: Oregon, Montana, New Hampshire, Delaware, and Alaska (though Alaska allows local jurisdictions to impose their own sales tax). If you're located in — or shipping to — one of these states, purchases generally won't include state sales tax, though local taxes may still apply in Alaska specifically.
For a broader look at how state tax policy varies across income tax as well as sales tax, our guide on states with no income tax covers the related landscape of state tax-friendly locations, and our detailed breakdown of federal vs state income tax in the USA explains how these systems interact more broadly.
Common Misconceptions About Online Sales Tax
- "Online purchases are always tax-free" — This was true before 2018, but the Wayfair decision fundamentally changed this; most online purchases today include sales tax.
- "If I'm not charged sales tax, I owe nothing" — Technically, use tax may still apply, even if rarely enforced against individual consumers.
- "Small sellers never have to collect sales tax" — Only true until they cross a state's specific nexus threshold, which can happen faster than expected with rapid growth.
- "Amazon sellers don't need to worry about sales tax at all" — Marketplace facilitator laws cover marketplace sales, but sellers with their own direct sales channels still need to track nexus separately.
- "All states tax the same way" — Rates, thresholds, exemptions, and even destination vs origin-based rules vary significantly state by state.
Why Use Free Calculators for Sales Tax Planning
Understanding exactly what sales tax applies to a purchase — or what you owe as a seller — requires more than guesswork, especially given how much these rules vary by state and address. At Free Calculators, our tools are built around current state and local rate data, giving you accurate figures instead of assumptions.
Whether you're a shopper checking an expected total or a business owner tracking multi-state obligations, explore our full suite of free tax tools to get clarity on exactly what applies to your situation.
FAQs About Sales Tax on Online Purchases
Do you pay sales tax on online purchases? Yes, in most cases. Since the 2018 Wayfair Supreme Court decision, states can require online retailers to collect sales tax based on economic activity, even without a physical presence in that state, meaning most online purchases include applicable sales tax.
Why do some online stores not charge sales tax? This typically happens when the seller hasn't crossed that state's economic nexus threshold, when purchasing from a no-sales-tax state, or when the specific product category is tax-exempt under that state's rules.
What is economic nexus for online sales tax? Economic nexus is a legal threshold — typically $100,000 in annual sales, or $500,000 in states like California and Texas — that, once crossed, requires an out-of-state seller to register and collect sales tax in that state, regardless of physical presence.
Do I owe use tax if I wasn't charged sales tax online? Technically, yes, in most states. Use tax is the consumer-side equivalent of sales tax, owed when a seller doesn't collect it. Enforcement against individual consumers is rare, though businesses face more scrutiny during audits.
Does Amazon automatically charge sales tax? Yes. Under marketplace facilitator laws adopted by every state with a sales tax, Amazon and similar platforms automatically calculate, collect, and remit sales tax on behalf of third-party sellers for marketplace transactions.
Are digital products subject to sales tax? This varies by state. Some states tax digital products identically to physical goods, while others exempt certain digital content entirely, making this one of the less standardized areas of state sales tax law.
Final Thoughts
The days of tax-free online shopping are largely behind us — since the 2018 Wayfair decision, most online purchases in the US include sales tax, calculated based on economic nexus rather than physical presence alone. Understanding why a specific purchase was or wasn't taxed comes down to a handful of factors: the seller's nexus status, your state's tax rules, and whether the product category qualifies for exemption. For online sellers, staying on top of nexus thresholds across states isn't optional — it's an ongoing compliance responsibility that grows more complex as sales volume increases.
Want to calculate exactly what sales tax applies to your situation? Try our free US Sales Tax Calculator by ZIP Code to get an accurate, location-specific breakdown in seconds.
For official, authoritative guidance, the Streamlined Sales Tax Governing Board and individual state Departments of Revenue remain the definitive sources to confirm current thresholds and requirements before making business decisions.