US Sales Tax Nexus Checker (free 2026 tool)

What this tool does

Identifies US states where your Delaware LLC has sales tax nexus based on physical presence, economic nexus thresholds (post-Wayfair), and affiliate relationships.

Who needs it

E-commerce and SaaS founders with US customers.

How it works

1. Enter business model (e-commerce, SaaS, services).
2. Enter states with physical presence.
3. Enter sales volume per state.
4. Tool flags states where nexus is triggered.

Inputs

• Business model
• Physical-presence states
• Per-state sales volume

Output

States requiring sales tax registration with thresholds.

What does the Sales Tax Nexus Checker actually compute?

This tool answers one narrow but high-stakes question for a Delaware LLC owner: in which US states do you have a legal obligation to register for, collect, and remit sales tax? It does that by reading three pieces of information you supply: your business model (e-commerce, SaaS, or services), the states where you hold a physical presence, and your sales volume in each state. It then maps that profile against the two doctrines that create a sales tax obligation in the United States: physical presence nexus and economic nexus. The output is a list of states that require sales tax registration, alongside the threshold that triggered the flag in each one.

The reason this matters to a non-resident founder is that sales tax in the US is not federal. There is no single national rate and no single national filing. Each state sets its own rules, its own thresholds, and its own definitions of what counts as a taxable sale. A Delaware LLC does not pay Delaware sales tax on out-of-state sales, because Delaware has no state sales tax at all. That fact misleads many founders into believing their LLC has no sales tax exposure anywhere. The truth is the opposite: your obligation follows your customers and your operations, not the state your LLC was formed in. The checker exists to translate "where are my customers and assets" into "where must I register," so you can see your real footprint before a state tax authority sees it for you.

Why does forming in Delaware not exempt you from sales tax?

Delaware is one of a small number of states with no general sales tax, and that is a genuine advantage when you sell to a customer physically located in Delaware. But forming your LLC in Delaware is a question of corporate law, not tax sourcing. Your Certificate of Formation costs $110 and establishes the legal entity. It does not change where the sale is deemed to occur for sales tax purposes. Sales tax is generally destination-based, meaning the rate and the obligation are tied to where the buyer takes delivery of the product or service, not where the seller is incorporated.

Because of this, the checker never returns Delaware as a nexus state on the basis of formation alone. If you sell a physical product to a customer in Texas, the Texas rules apply to that sale, regardless of the fact that your LLC paperwork lives in Dover. The franchise tax you pay to Delaware (a flat $300 due each June 1, with a $200 late penalty plus 1.5% interest per month if you miss it) is a separate entity-level levy and has nothing to do with sales tax collected from buyers. Keep these two streams mentally separate: franchise tax is what your LLC owes Delaware for existing, while sales tax is what your buyers owe their own states and what you are legally required to collect on those states' behalf. The tool only addresses the second.

How do you read the business model input?

The first input asks you to classify your business as e-commerce, SaaS, or services, and that choice changes how the rest of the analysis runs. The classification matters because states do not treat all sales the same way. Tangible goods sold by an e-commerce business are taxable in nearly every state with a sales tax. Software delivered as a service, by contrast, is taxable in some states and fully exempt in others, and the line between "software" and "a service" is drawn differently from one jurisdiction to the next. Pure professional services are exempt in many states but taxable in a meaningful minority.

So when you select SaaS, the tool understands that hitting an economic threshold in a given state does not automatically mean you owe tax there, because that state may not tax your category of product at all. When you select e-commerce, the assumption flips toward taxability, because physical goods are the default taxable category. Choosing the wrong model is the single most common way founders get a misleading result. A founder who sells a downloadable template but selects "services" may understate exposure, while one who sells consulting but selects "e-commerce" may overstate it. Pick the model that matches what the customer actually receives at the moment of sale, and if you sell more than one type, run the checker separately for each revenue line so the thresholds are not blended together in a way that hides a real obligation.

How do physical-presence states create nexus?

Physical presence is the older of the two nexus doctrines and the one that is hardest to argue your way out of. If your LLC has a tangible connection to a state, you have nexus there from the first dollar of sales, with no minimum threshold to cross. The second input collects these states. The checker treats any state you list here as an automatic nexus state for your taxable product categories, because physical presence does not depend on volume the way economic nexus does.

• An office, storefront, warehouse, or any leased or owned space in the state.
• Employees or contractors who live and work in the state on your behalf.
• Inventory stored in the state, including stock held in a third-party fulfillment warehouse you do not own.
• Owned equipment or servers physically located in the state.
• Regular in-person activity such as trade shows or sales visits, depending on the state's frequency rules.

The inventory point catches many non-resident founders by surprise. If you use a marketplace fulfillment program that moves your goods into warehouses across several states, each of those states can assert physical presence nexus over you, even though you never chose where your inventory landed. A founder running a Delaware LLC from outside the US who ships to a fulfillment center in Pennsylvania, California, and Texas may have physical presence in all three before making a single direct sale. List every state where your goods or people actually sit. Leaving one out does not remove the obligation, it only removes it from the tool's output and leaves you with a blind spot a state auditor can later fill.

What is economic nexus and where did the thresholds come from?

Economic nexus is the rule the tool leans on most for a remote founder. It says a state can require you to collect sales tax based purely on the volume of business you do with its residents, even if you have no office, no staff, and no inventory there. This doctrine became enforceable nationwide after the 2018 Supreme Court decision in South Dakota v. Wayfair, which overturned the older requirement that a seller needed physical presence before a state could tax it. After Wayfair, states were free to set sales-volume or transaction-count thresholds, and almost every state with a sales tax did so.

The most widely adopted threshold, and the one South Dakota itself used, is $100,000 in sales or 200 separate transactions into the state within a twelve-month period. Many states copied that figure exactly, while others set theirs at $250,000 or $500,000 or dropped the transaction-count test entirely. This is why your per-state sales volume input is the heart of the economic-nexus check: the tool compares your volume in each state against that state's threshold and flags the ones you have crossed. A founder with $130,000 of sales into a state using the $100,000 standard is over the line and will be flagged, while the same $130,000 spread thinly across forty states might cross no single threshold at all. The geography of your revenue matters as much as the total, which is exactly why the tool asks you to break sales down by state rather than report one national figure.

How should you enter per-state sales volume?

The per-state sales volume input is where accuracy pays off most, because a small error here can flip a state from clear to flagged or hide a real obligation. Enter your gross sales delivered to buyers in each state over a rolling twelve-month window, not your net profit and not your worldwide total. Most states measure their threshold against gross receipts before you subtract costs, refunds, or fees, although a handful exclude sales made through a marketplace that already collects tax on your behalf. Use the destination of the buyer, since that is how sales tax is sourced, rather than where you invoiced from.

Pull these figures from your payment processor or store platform, which can usually report revenue by the customer's shipping or billing state. If you sell through a marketplace that collects and remits tax for you under marketplace facilitator laws, those sales may still count toward your threshold in some states even though you owe no additional tax on them, so keep them in the figure unless you have confirmed a specific state excludes them. When in doubt, enter the higher gross figure: the tool is meant to surface risk, and a conservative input gives you a warning earlier rather than later. Round to whole dollars and update the numbers each quarter, because economic nexus is not a one-time test. You can cross a threshold mid-year as a single large customer or a seasonal spike pushes you over, and the obligation begins shortly after you cross, not at the start of the following tax year.

How do you read the output and the threshold it shows?

The output is a list of states that require sales tax registration, each paired with the threshold that triggered the flag. Reading it correctly means understanding why a state appears. A state flagged through physical presence appears because you listed it as a presence state, and the threshold shown will reflect that any volume is enough. A state flagged through economic nexus appears because your entered volume met or exceeded that state's sales or transaction threshold, and the figure shown is the line you crossed.

A state that does not appear in the output is not a permanent all-clear. It means that, based on the numbers you entered, you have not yet triggered nexus there. If your sales into that state grow, or you place inventory there, the answer can change at your next run. Treat the output as a snapshot tied to the inputs you gave, not a certificate. The practical next step for each flagged state is to register for a sales tax permit with that state's revenue department before you collect any tax, because collecting tax without a permit is itself a violation in most states. Once registered, you collect at the correct rate, file on the schedule the state assigns (monthly, quarterly, or annually depending on your volume), and remit what you collected. The tool tells you where the obligation exists, and registration plus filing is how you satisfy it.

A worked example: a SaaS founder with US customers

Consider a non-resident founder whose Delaware LLC sells a subscription analytics product. She has no US office, no US employees, and no inventory, because the product is delivered entirely over the internet. She selects SaaS as her business model and lists no physical-presence states. Her revenue over the last twelve months is $140,000 from California, $90,000 from New York, $40,000 from Florida, and roughly $30,000 spread across twenty other states in small amounts. She enters each state's figure in the per-state input.

The checker flags California, because $140,000 exceeds California's economic threshold and California taxes some software products. It does not flag the twenty small states, because none individually approaches a threshold. New York at $90,000 sits below a $100,000 line, but New York also uses a transaction count, so if those sales came from more than the state's transaction threshold she could still be flagged, which is why entering transaction-heavy revenue accurately matters. Florida at $40,000 is well under. The lesson she takes from the output is that her exposure is concentrated, not spread evenly, and that her single largest market is the one that needs a permit. Because she chose SaaS rather than e-commerce, the tool also reminds her that taxability of her product varies by state, so even a flagged state may treat her specific subscription as exempt. Her action is to confirm California's treatment of her product category, register if it is taxable, and re-run the tool each quarter as sales climb.

A worked example: an e-commerce founder using fulfillment warehouses

Now consider a founder selling physical phone accessories through his Delaware LLC. He ships using a marketplace fulfillment program that stores his inventory in warehouses in Pennsylvania, Texas, and Nevada. He selects e-commerce as his model. The inventory location is the decisive fact here, so he lists Pennsylvania, Texas, and Nevada as physical-presence states, because his goods physically sit in those states. His direct sales total $60,000 nationwide, none of it large enough to cross an economic threshold on its own.

Despite modest sales, the checker flags Pennsylvania, Texas, and Nevada, because physical presence creates nexus from the first dollar with no threshold to clear. This surprises him, since his total revenue is small, but it is the correct result: stored inventory is a tangible connection. The output shows three states tied to presence rather than volume. His next steps differ from the SaaS founder's. He registers in all three states regardless of how little he sold there, and he checks whether the marketplace itself already collects and remits tax on his behalf under each state's marketplace facilitator law, which can shift the actual remittance burden even while the registration obligation remains. The takeaway is that a founder can have a heavy registration footprint on tiny revenue purely because of where a fulfillment program parked his goods, and only a presence-aware tool surfaces that.

What are the most common mistakes founders make with this tool?

The errors that produce a wrong answer cluster around a few inputs, and knowing them lets you avoid a false sense of safety. The most damaging mistake is entering one national sales figure instead of breaking revenue down by state, which makes economic nexus impossible to assess correctly. The second is forgetting inventory held in third-party warehouses, which silently drops real physical-presence states from the output. The third is misclassifying the business model, which skews every downstream judgment about taxability.

• Assuming a Delaware LLC owes no sales tax anywhere because Delaware has no sales tax.
• Reporting net revenue when states measure thresholds against gross receipts.
• Excluding marketplace sales from the threshold figure without confirming a given state allows that exclusion.
• Treating a clear result as permanent rather than re-checking as sales grow.
• Confusing sales tax with the Delaware franchise tax or with federal filings like Form 5472 and Form 1120.

That last point deserves emphasis because the filings get conflated constantly. A single-member foreign-owned Delaware LLC must file Form 5472 along with a pro forma Form 1120 each year, and missing it carries a $25,000 penalty. That is a federal information return tied to your foreign ownership, and it has no connection to whether you collect sales tax in California. The nexus checker speaks only to state sales tax. Keeping these obligations in separate mental boxes prevents both the panic of thinking you owe everything everywhere and the complacency of thinking one clean filing covers them all.

What edge cases does the checker not fully resolve?

The tool is built to surface obligations quickly, but several situations sit at the edge of what any threshold check can decide on its own. The clearest is product taxability for SaaS and digital goods. Crossing a state's economic threshold tells you the state can reach you, but whether your specific product is taxable in that state is a separate determination that depends on how the state classifies software, digital downloads, and information services. A flag for a SaaS business is a prompt to verify taxability, not a final ruling that tax is owed.

Other edge cases include transaction-count thresholds that catch low-revenue, high-volume sellers, trailing nexus where an obligation continues for a period after you drop below a threshold, and the interaction between marketplace facilitator collection and your own direct sales. Some states count only your direct sales toward your threshold once a marketplace handles its own, while others count everything. There is also the timing question: economic nexus typically begins shortly after you cross the line during a measurement period, not on a clean January 1 boundary, so a mid-year spike can create a mid-year obligation. The checker gives you the state and the threshold, which is enough to know where to look, but a flagged state with unusual facts, a borderline volume, or a digital product warrants a direct read of that state's current rules before you decide how to register and what rate to apply.

What should you do after the checker flags a state?

Once the output names a state, the work shifts from diagnosis to compliance, and the order of steps matters. First, confirm the flag's basis, presence or economic volume, so you understand whether the obligation depends on facts that could change. Second, for economic-nexus flags involving SaaS or digital goods, confirm your product is actually taxable in that state before registering, since registering where you owe nothing creates filing duties without revenue benefit. Third, register for a sales tax permit with that state's revenue authority, because you must hold a permit before you legally collect.

After registration, configure your checkout or billing system to collect the correct destination rate in that state, file returns on the cadence the state assigns, and remit what you collected by each due date. Keep a record of the inputs you used in the checker and the date you ran it, so you can show why you registered when you did if a state ever asks. Re-run the tool at least quarterly, and immediately whenever you place inventory in a new state or land a large customer, because both events can create nexus between scheduled checks. The checker is the front end of an ongoing process rather than a one-time clearance. Used that way, with honest state-level inputs and a fresh run each quarter, it keeps a non-resident founder's sales tax footprint visible and manageable instead of letting it accumulate into a back-tax problem discovered years later during diligence or an audit.