If you sell online, you generally have to collect sales tax in any state where you cross an economic threshold (most commonly $100,000 in annual sales into that state) or where you have a physical presence such as inventory, an office, or employees. That single rule now governs online sales tax by state across the 45 states and the District of Columbia that impose a statewide sales tax. The thresholds, rates, taxable products, and filing rules vary enough that a seller shipping nationwide can end up registered in dozens of jurisdictions at once.
When You Owe Sales Tax in Another State
Before 2018, a state could only force you to collect sales tax if you had a physical presence there. The Supreme Court changed that in South Dakota v. Wayfair, Inc., holding that a state can require tax collection based on economic activity alone, even from a seller with no office, warehouse, or employee in the state.1Legal Information Institute. South Dakota v. Wayfair, Inc. Every sales-tax state has since passed its own economic nexus law.
The most common trigger is $100,000 in gross sales delivered into a state during a calendar year. Some states also trigger the obligation at 200 separate transactions, though that alternative is shrinking. As of early 2026, roughly half the states with economic nexus laws still include a transaction-count option; the rest rely on revenue alone. A handful set higher revenue bars, notably $500,000.
The measurement period is where sellers get tripped up. Most states look at the previous calendar year or the current calendar year, whichever you exceed first. A few use a rolling twelve-month window that doesn’t align with the calendar at all. If you hit $100,000 in sales to a state in July, you likely owe registration before year-end, not the following January. Some states require collection on the very next transaction after you cross the line; others give you 30 to 90 days to register and start collecting.
How each state defines the $100,000 also matters. Some count all gross revenue shipped into the state, including exempt and wholesale sales. Others count only taxable retail transactions. That distinction can be the difference between owing registration and staying below the line, so if you sell a mix of taxable and exempt products, check each state’s definition individually.
Physical Presence Still Triggers Collection
Economic nexus gets the attention, but old-fashioned physical presence creates the same obligation and often kicks in with the first sale. An office, a storefront, a warehouse, or an employee working in a state gives you physical nexus there regardless of sales volume. Storing inventory in a third-party fulfillment center counts too, which catches sellers who use multi-warehouse shipping networks without realizing each warehouse location creates a tax obligation.
Temporary activities can also create nexus. Sending a sales rep to a trade show, or keeping product samples at a local facility, is usually enough. Owning or leasing equipment in a state, such as a delivery vehicle or server hardware, can do it as well.
About fifteen states enforce click-through nexus laws. If you pay commissions to in-state residents who refer customers through affiliate links, you may be treated as having a physical presence. These laws typically include a minimum sales threshold before they apply, so a single affiliate earning small commissions usually won’t trigger the obligation, but a robust affiliate program generating significant referral revenue in a state can.
When the Marketplace Collects for You
If you sell through Amazon, eBay, Etsy, Walmart Marketplace, or a similar platform, the platform almost certainly handles sales tax collection for you. Nearly all sales-tax states have enacted marketplace facilitator laws that shift collection and remittance from individual sellers to the platform itself. The platform calculates the correct rate based on the buyer’s address, collects the tax at checkout, and sends it to the state.
This is the single biggest compliance simplifier for small online sellers. If all your sales flow through a covered marketplace, the platform bears the audit risk on those transactions. Most states require the facilitator to give sellers documentation showing the tax collected, which protects you if questions arise later.
The catch comes when you sell through both a marketplace and your own independent website. Facilitator laws only cover sales made on the platform. If your direct website sales exceed a state’s economic nexus threshold on their own, you still owe registration and collection for that portion. Some states also require you to file returns even when a facilitator collected all the tax on your behalf. In those states, you report marketplace sales on your return but claim a credit or deduction for what the facilitator already remitted, effectively filing a zero-liability return.2Streamlined Sales Tax Governing Board. Marketplace Seller State Guidance Skipping those returns can generate late-filing penalties even though you owe nothing.
The Five States With No Statewide Sales Tax
Alaska, Delaware, Montana, New Hampshire, and Oregon impose no statewide sales tax. Sellers shipping into these states generally have no state-level collection requirement regardless of sales volume. But “no statewide tax” does not always mean “no tax at all.”
Alaska is the exception. While the state itself charges no sales tax, it allows local municipalities to levy their own, and many do. The Alaska Remote Seller Sales Tax Commission runs a centralized registration portal so remote sellers can file with all participating local jurisdictions in one place rather than registering city by city.3Alaska Remote Seller Sales Tax Commission. Alaska Remote Seller Sales Tax Commission If your sales into Alaska exceed the commission’s threshold, you may need to register through this portal.
Delaware has no sales tax but does impose a gross receipts tax on businesses operating within the state. That tax falls on the seller’s total revenue rather than on the consumer at checkout, so it works differently from a traditional sales tax. Remote sellers with no Delaware presence generally don’t encounter it; businesses physically located there pay it on every dollar of revenue. Montana, New Hampshire, and Oregon are genuinely tax-free at both state and local level, making them the simplest states in the country for remote seller compliance.
Which Products and Services Are Taxable
Most physical goods shipped to a customer are taxable in states with a sales tax, but exemptions vary widely. Groceries are partially or fully exempt in a majority of states. Clothing is fully exempt in a handful of states and exempt below a price cap in a few others. Prescription medications are exempt almost everywhere. These exemptions apply to online purchases just as they do to in-store purchases, so an online grocery service may collect tax on snack foods but not on staples, depending on the destination.
Digital products are where it gets complicated. There is no uniform national standard for taxing digital downloads, streaming, or cloud software.4National Conference of State Legislatures. Brief Taxation of Digital Products Some states tax digital music, e-books, and streaming video the same way they tax the physical equivalents. Others exempt digital goods entirely. The Streamlined Sales Tax Agreement created a menu of digital product categories that member states can choose to tax or not, and states pick and choose, leading to a patchwork even among states that otherwise cooperate on tax simplification.
Software as a Service is more fragmented still. Roughly twenty states tax SaaS in some form, but they disagree on why. Some classify it as tangible personal property because it involves software. Others treat it as a taxable data processing service. Others exempt it entirely because no physical product changes hands. A few states split the difference: one major state taxes only 80 percent of SaaS charges under a data processing classification, while another taxes SaaS only when sold for business use and exempts personal-use subscriptions. If you sell SaaS or digital products, check each state’s classification individually rather than assuming one rule applies.
Figuring Out Which Rate to Charge
Knowing you owe tax is only half the problem. You also need the right rate. States use either origin-based sourcing (charge the rate where your business sits) or destination-based sourcing (charge the rate where the buyer receives the item). For online sellers, destination-based sourcing dominates. About three-quarters of sales-tax states use destination-based rules, and even most origin-based states switch to destination-based sourcing for interstate transactions.
Thirty-eight states allow local jurisdictions to add their own sales tax on top of the state rate. Local additions range from fractions of a percent to over five percent, and in some jurisdictions the local rate rivals the state rate itself.5Tax Foundation. State and Local Sales Tax Rates, 2026 Combined state and local rates can exceed 10 percent in parts of the country with the highest local levies. Jurisdiction boundaries don’t follow zip codes cleanly: two addresses in the same zip code can fall in different tax districts with different rates. A handful of “home rule” cities administer their own sales tax independently from the state, meaning a business may need to register and file a separate return directly with the city.
This is where automated tax calculation software earns its keep. The Streamlined Sales Tax Agreement offers free tax calculation through Certified Service Providers for sellers registered in member states. Five providers are currently certified, and their services are free to qualifying sellers in the 23 full member states.6Streamlined Sales Tax Governing Board. Certified Service Providers About Using a CSP also carries liability protection: if the software applies the wrong rate, the seller is generally shielded from penalties on the error. For sellers in non-member states, commercial tax software from companies like Avalara, TaxJar, or Vertex handles the same rate lookups for a fee.
Registering and Filing in Each State
Once you determine where you have nexus, register for a sales tax permit in each state before you begin collecting. Registration is free in most states, though roughly a dozen charge fees ranging from $5 to $100. The Streamlined Sales Tax system offers a single online registration portal covering all 23 member states at once, which saves considerable time if you sell nationwide.7Streamlined Sales Tax Governing Board. Streamlined Sales and Use Tax Agreement Non-member states require individual registration through each state’s tax agency.
After registration, the state assigns you a filing frequency (typically monthly, quarterly, or annually) based on your expected tax liability there. High-volume sellers usually file monthly; lower-volume sellers may file quarterly or annually. The threshold for monthly filing varies from a few hundred dollars per month in tax liability in some states to $30,000 per year in others. Most returns are due by the 20th or the last day of the month following the reporting period, though exact dates vary.
You must file a return for every period, even if you had zero sales in that state. Missing a zero-dollar return still counts as a late filing and can generate penalties. That is the compliance burden that catches small sellers off guard: registering in 20 states means filing 20 returns every quarter or month, even when most show no activity. Some states offer a timely filing credit or discount for filing and paying on time, which partially offsets the administrative cost.
Exemption Certificates
Not every sale to a customer in a taxable state actually requires tax collection. Wholesale buyers, nonprofits, government agencies, and certain other exempt purchasers can provide an exemption certificate that relieves you of the collection obligation on that transaction. The burden of proof falls squarely on the seller.
If you’re audited and can’t produce a valid certificate for an exempt sale, the state treats it as a taxable sale and you owe the tax plus potential penalties. Certificates must be complete, current, and match the type of exemption claimed. Collecting the wrong type of certificate is treated the same as having no certificate at all. A blanket certificate covers ongoing purchases from the same exempt buyer without requiring a new form each time, which reduces paperwork for repeat wholesale customers.
Retain exemption certificates for at least as long as the state’s statute of limitations for sales tax audits, which in most states runs three to four years. Even if you only make exempt sales in a state, those sales can still count toward the economic nexus threshold, meaning you may need to register and collect certificates even when you never actually collect tax.
If You Missed Collecting: Penalties and Voluntary Disclosure
States take sales tax noncompliance seriously because the tax belongs to the state, not to you. When you collect sales tax from a customer and don’t remit it, that’s treated more like holding government funds than underpaying your own taxes. Late filing penalties typically start at 5 to 10 percent of the tax due for the first month and can climb to 25 or 30 percent for extended delinquency, plus interest from the original due date. Fraud or willful failure to remit collected tax can carry penalties of double the tax owed, and in extreme cases, criminal prosecution.
If you discover you should have been collecting tax in a state but weren’t, a Voluntary Disclosure Agreement can significantly reduce your exposure. Most states participate in the Multistate Tax Commission’s National Nexus Program, which streamlines the VDA process. The key benefit is a limited lookback period. Instead of assessing you for every year you should have been registered, the state typically limits the assessment to three or four years of back taxes.8Multistate Tax Commission. Lookback Periods for States Participating in National Nexus Program Most participating states use a 36-month lookback, with some extending to 48 months. The agreement also typically waives penalties, leaving you responsible only for the tax itself plus interest.
The window closes once a state contacts you first. If you receive an audit notice or inquiry letter, you’ve lost the ability to come forward voluntarily in that state. Sellers who realize they have exposure in multiple states often file VDAs in several states at once to clean up their compliance before any state catches the gap.