eCommerce Sales Tax & Economic Nexus FAQ for Online Sellers

Online sellers face a sales tax environment that has changed dramatically since 2018. Economic nexus rules mean you can owe sales tax in dozens of states based on sales volume alone — with no warehouse, office, or employee required. Marketplace facilitator laws, FBA inventory nexus, product taxability rules, and exempt customer management all add additional layers of complexity that grow with every new product, channel, and customer base. This FAQ covers the most common sales tax questions from e-commerce businesses, from nexus basics and marketplace rules to use tax, exempt customers, and building compliance infrastructure that scales. For help with your specific situation, contact ACTSOLV to schedule a consultation.

Do online sellers have to collect sales tax in every state?

No — but the obligation is much broader than most sellers realize. Before the Supreme Court's 2018 South Dakota v. Wayfair decision, online sellers generally only had to collect sales tax in states where they had a physical presence. That changed everything. Today, virtually every state enforces economic nexus rules, meaning you are required to collect and remit sales tax in any state where your sales to customers exceed that state's threshold — even with zero physical presence there.

Most states use a threshold of $100,000 in annual sales or 200 transactions. Five states have no sales tax: Alaska, Delaware, Montana, New Hampshire, and Oregon. In every other state, once you cross the threshold you must register, collect the correct rate, and file returns on the required schedule. Review economic nexus thresholds by state to understand exactly where your current sales volume is creating obligations.

What is economic nexus and how does it affect e-commerce sellers?

Economic nexus is the sales tax collection obligation that arises when your sales to customers in a state cross that state's threshold — regardless of physical presence. For e-commerce sellers, this means that as your business grows and you ship more products to more states, you will cross thresholds in those states and acquire new registration and collection obligations. This happens automatically, without any action on your part, simply as a consequence of growth.

Most states use $100,000 in annual sales or 200 transactions as the standard threshold. Some larger states have higher thresholds, and a number of states have eliminated the transaction count requirement, relying solely on dollar volume. The practical challenge is that sellers need to be monitoring their sales data by state on an ongoing basis to identify when new thresholds are being approached — because the obligation begins the day you cross the threshold, not the day you discover it. Read more on how fast-growing companies manage expanding nexus obligations as they scale into new markets.

What are marketplace facilitator laws and how do they affect my obligations?

Marketplace facilitator laws require platforms like Amazon, eBay, Etsy, and Walmart to collect and remit sales tax on behalf of third-party sellers using their platforms. If you sell exclusively through these marketplaces, the marketplace is handling sales tax collection for those transactions in states with marketplace facilitator laws — which now covers essentially all states with a sales tax.

However, two important nuances apply. First, if you also operate your own website or sell through other direct channels, you are responsible for sales tax collection on those transactions yourself. Second, marketplace sales can still count toward your economic nexus thresholds, meaning selling through Amazon or Etsy could push you over the threshold in a state and create collection obligations for your direct sales even if the marketplace handles the marketplace transactions. Marketplace facilitator coverage does not eliminate your compliance exposure — it just shifts where it sits. AUTOSOLV helps manage the direct-channel obligations that marketplace sellers often overlook.

How does Amazon FBA create sales tax nexus for sellers?

Amazon's Fulfillment by Amazon program stores seller inventory in Amazon fulfillment centers distributed across the country. In most states, having inventory physically stored in a state — even inventory owned by a third party on your behalf — creates physical nexus in that state. This means FBA sellers may have nexus in 20 or more states depending on which Amazon fulfillment centers hold their products at any given time.

While Amazon handles sales tax collection on marketplace transactions in states with marketplace facilitator laws, the physical nexus created by FBA inventory may still create filing obligations for any direct sales you make through your own website or other off-marketplace channels. FBA sellers should periodically audit which states are holding their inventory and review whether those states create obligations for their non-marketplace sales. This is a frequently missed exposure point, particularly for sellers who primarily think of Amazon as handling their tax obligations. Read more about how to build a systematic approach to managing tax obligations across channels.

What is destination-based vs. origin-based sales tax sourcing for online sales?

Most states use destination-based sourcing for online sales, meaning sales tax is calculated based on where the buyer is located — the ship-to address. This is the standard rule for the vast majority of e-commerce transactions. A smaller number of states use origin-based sourcing, meaning tax is based on where the seller is located, though out-of-state sellers typically still follow destination-based rules even in origin-based states.

For e-commerce sellers shipping nationwide, destination-based sourcing means you need to apply the correct combined state, county, and city tax rate for each buyer's specific address — not just a statewide rate. Tax rates can vary significantly within a single state depending on the city and county, so applying a single rate per state leads to both over-collection and under-collection errors. Accurate destination-based tax calculation requires either a real-time tax calculation engine that handles rate lookups automatically, or a very disciplined manual process — and at any meaningful sales volume, only automation is reliable. AUTOSOLV handles destination-based rate calculation automatically across all U.S. jurisdictions.

How do e-commerce sellers handle exempt customers and resale certificates?

Sellers who transact with tax-exempt buyers — resellers, manufacturers, nonprofits, government entities — must collect valid exemption certificates before allowing any exemption. Without a certificate on file, the sale is presumed taxable. If you fail to collect tax on a taxable sale, the liability falls on you as the seller.

The challenge for online sellers is that the certificate collection process has to be digital and integrated into the checkout or customer onboarding workflow rather than a paper-based manual process. CertSOLV integrates with e-commerce platforms to collect and validate exemption certificates at the point of sale, verify them against state-specific requirements, store them securely, and flag them for renewal before expiration. This keeps exempt customers transacting smoothly without manual back-and-forth while maintaining the documentation needed for audit defense. Read more about automating tax exemption validation for online sellers and the most common certificate management mistakes.

Are shipping and handling charges taxable for online sales?

Shipping taxability varies significantly by state and by how the charge appears on the invoice. Some states always tax shipping charges as part of the sale. Others exempt shipping when it is separately stated as a distinct line item on the invoice at actual cost. A few states base taxability on whether the underlying product being shipped is taxable. Generally, when shipping is bundled into the product price or combined with handling on a single line, it is more likely to be taxable. When shipping is broken out as a separate, clearly labeled line item, it is more likely to qualify for exemption in states that allow it.

Because the rules differ across all 45 states with sales tax, e-commerce sellers need to configure their shopping cart tax settings to handle shipping charges correctly on a state-by-state basis rather than applying a blanket rule. This is a common source of both over-collection and under-collection that surfaces in audits. Read more about how billing and pricing decisions affect your tax exposure.

How does product taxability work for online sellers with diverse product catalogs?

Product taxability is one of the most complex aspects of e-commerce sales tax because the rules are highly state-specific and category-specific. A product that is fully taxable in one state may be exempt, reduced-rate, or taxable only above a certain price threshold in another. Common product categories with highly variable taxability include groceries, clothing, dietary supplements, medical devices, and digital goods. For example, clothing is generally exempt in Pennsylvania and New York under a certain price threshold, but taxable in most other states. Groceries are exempt or reduced-rate in many states but fully taxable in others.

For e-commerce sellers with large or diverse catalogs, maintaining accurate product taxability classifications in your tax calculation system is critical. Misclassifications are a common audit finding and can result in assessments for years of under-collected tax — along with penalties and interest. If your product mix includes anything in a gray-area category, a taxability review is worth conducting before an auditor does it for you. Read about building the business case for tax technology to manage product taxability at scale.

What is use tax and when do e-commerce businesses owe it?

Use tax is the complement to sales tax and applies when a business purchases taxable goods or services without paying sales tax — typically because the vendor was from another state or was not registered to collect in yours. For e-commerce businesses, use tax obligations most commonly arise on out-of-state inventory purchases, equipment and packaging materials, software and SaaS tools used in the business, and goods withdrawn from inventory for internal use rather than sale.

Use tax is self-assessed and remitted directly to the state by the purchaser — it does not get automatically collected the way sales tax does at the point of sale. This makes it easy to overlook, and unaddressed use tax exposure is one of the most consistent findings in state audits of e-commerce businesses. AUTOSOLV automates use tax accrual by evaluating vendor invoices against current state taxability rules and booking the correct liability, so nothing falls through the cracks. Learn more about why use tax is the most commonly overlooked compliance obligation for online businesses.

What sales tax records do e-commerce sellers need to maintain for audits?

E-commerce sellers should maintain complete transaction-level records for every sale: transaction date, customer name, ship-to address, product description, taxable and exempt amounts, tax collected, and the rate applied. For exempt transactions, valid exemption certificates must be tied to each exempted customer or transaction. Filing records — returns submitted, amounts remitted, and payment confirmations — should be retained by state. Most states look back three to four years in audits, so records should be kept for at least that long, and some states can go further under certain circumstances.

The volume of transactions in e-commerce makes manual record-keeping impractical at any meaningful scale. Integration between your e-commerce platform, tax calculation engine, and accounting system is the only sustainable approach to maintaining audit-ready records. CertSOLV maintains a centralized, searchable repository of all exemption certificates with full audit trails, and AUTOSOLV ensures that every transaction is correctly accrued and documented. See the ACTSOLV compliance case study to see how this works in practice for a high-transaction business.

How should growing e-commerce businesses approach scaling their tax compliance?

The most common mistake growing e-commerce businesses make is treating sales tax compliance as a problem to solve later. Economic nexus thresholds are crossed quietly as the business grows, and by the time the exposure is discovered — during due diligence for a fundraise or acquisition, or during an audit — there are often multiple years of back liability in multiple states to address. The cost of remediation is always higher than the cost of prevention.

The right approach is to build compliance infrastructure early: configure accurate tax calculation in your platform, automate exemption certificate collection for exempt customers, monitor your state-by-state sales data to catch new nexus thresholds before you cross them, and run a systematic use tax review on your vendor spend. CertSOLV and AUTOSOLV integrate with e-commerce platforms and ERPs to provide this infrastructure at any stage of growth. Read 5 ways to build a business case for sales tax technology for guidance on making the investment decision, and understand the revenue risk of waiting too long.