A company sells into twenty states, has staff in one, and holds inventory in two. On paper that is a simple business. In sales tax terms it may have obligations in a dozen jurisdictions, none of which announced themselves.
Nothing arrived to mark the moment any of those obligations began. Revenue crossed a line in a state’s statute, the duty to collect attached, and the company kept invoicing exactly as before.
That gap between when the obligation starts and when anyone notices is where most of the cost in this area accumulates.
Physical Presence Stopped Being The Test
For decades the rule was physical presence. No office, no employees, no inventory in a state meant no obligation to collect its tax. Finance teams could reason about exposure by looking at a map of facilities.
The 2018 Supreme Court decision in South Dakota v. Wayfair ended that. States were permitted to base collection obligations on economic activity alone, and within two years nearly all of them had done so.
Thresholds commonly sit around $100,000 in annual sales into a state, though the figures are not uniform and some states also count transaction volume separately. Both tests matter for companies with low average order values, where a business can cross a transaction count long before it approaches the revenue figure.
The obligation attaches when the threshold is met. It does not wait for the company to register, and no state sends a notice when it happens.
Forty-Six Different Systems
There is no federal sales tax. Forty-five states plus the District of Columbia operate their own, each with distinct rules on rates, filing calendars, exemption handling, and what counts as taxable in the first place.
Local jurisdictions add rates on top. A single state can contain hundreds of effective rates depending on the delivery address, and in home-rule states certain cities administer their own tax with separate registration and separate returns.
This is why a national approach built on one rate table does not survive contact with actual operations. The calculation has to resolve to the specific delivery address, and the filing obligations vary by state in frequency, format, and due date.
Software And Services Are Not Automatically Exempt
Companies selling digital products often assume this is a physical goods problem. It is not.
State treatment of software, digital downloads, streaming media, and software as a service varies considerably. Some states tax SaaS outright. Some tax it only when delivered in particular ways. Some exempt it entirely, and several have changed position within the last few years.
The result is a subscription product that is taxable in one state and exempt in the next, with the answer turning on a definition written before the category existed. The boundary between a nontaxable professional service and a taxable digital product is genuinely ambiguous in several jurisdictions, and companies frequently classify by intuition rather than by reading the state’s own guidance.
Getting sales tax compliance services functioning properly is less about the calculation engine than about establishing which definition applies to what the company actually sells, state by state, before the volume gets large.
Marketplace Sales Create False Comfort
Marketplace facilitator laws now require platforms to collect and remit on behalf of sellers in most states. That is a real reduction in burden for companies selling through them.
It also produces a specific error. A company selling through both a marketplace and its own website looks at the marketplace’s tax reporting, sees the obligation handled, and concludes it is covered. Only part of the revenue was ever in scope.
Direct website sales, wholesale arrangements, and subscription billing all sit outside that protection. So does any channel added later without the same review.
Certificates Are The Seller’s Burden
Selling to resellers or exempt organizations does not remove the obligation by itself.
The exemption holds only if a valid certificate was collected from the buyer and can be produced at audit. Missing paperwork means the tax gets assessed against the seller, not the customer who claimed the exemption.
Certificates also expire, vary in form by state, and need to match the transaction they cover. A folder of certificates gathered years ago and never reviewed is not the protection it appears to be.
Nobody Bills You Until They Do
The structural problem with sales tax is that unregistered companies are invisible until something prompts a state to look. That prompt might be a marketplace data request, a customer inquiry, a payment processor record, or a routine matching exercise.
When it arrives, the assessment covers the full period the obligation existed, plus penalties and interest. The tax was always meant to be collected from customers at the point of sale. Because it was not, the company pays it out of margin, on revenue recognized and spent long ago.
Voluntary disclosure agreements exist in most states and generally limit the lookback period in exchange for coming forward first. They are only available before the state makes contact, which is the entire reason timing matters more here than in most tax areas.
The Review Worth Running This Quarter
Pull the last three years of revenue and break it down by destination state. Compare each state total against that state’s economic thresholds, both revenue and transaction count, and note the month each was crossed.
Separate marketplace sales from direct sales, because only one of those is likely being handled.
Confirm what the company is actually selling in each state’s terms rather than in its own, particularly for anything digital.
Where a threshold was crossed and nothing was collected afterward, the exposure already exists and grows with every order. Every month without a decision narrows the options for resolving it on favorable terms.