Sales tax is a consumption tax levied by US state and local governments on the sale of goods (and increasingly services), collected by the seller from the buyer at point of sale and remitted to the relevant tax authority. Unlike VAT, it is a single-stage tax applied only at final sale, with no federal layer and over 13,000 local jurisdictions in play.
Sales tax is a consumption tax levied by US state and local governments on the sale of goods, and increasingly on services as well. The seller collects the tax from the buyer at the point of sale, holds it in trust, and remits it to the relevant tax authority on a defined filing schedule. The buyer ultimately bears the economic cost, while the seller carries the compliance burden.
The single most important distinction for AR teams operating cross-border is that sales tax is a single-stage tax. It is only collected at the final sale to the end consumer or business user. Value Added Tax (VAT), used in the European Union, the United Kingdom, and most of the rest of the world, is a multi-stage tax collected at every link in the supply chain, with input credits flowing through. That difference shapes everything: how invoices are formatted, how exemptions work, how refunds and credits are handled, and how systems calculate liability.
There is also no federal sales tax in the US. All sales tax is administered at state and local level, which is why compliance complexity is so much higher in the US than in any single VAT jurisdiction.
The headline numbers explain why multi-state sales tax is one of the hardest problems in AR. 45 states plus the District of Columbia impose a state-level sales tax. The five outliers (Oregon, Montana, New Hampshire, Delaware, and Alaska at state level) do not. On top of state rates, 38 states allow local jurisdictions (counties, cities, special districts) to add their own sales tax.
The result is more than 13,000 distinct sales tax jurisdictions in the US. Combined rates run from 0% in the no-tax states to over 10% in some cities. A single shipment to a customer's warehouse in one ZIP code can be taxed at a different rate than a shipment to their head office two streets away, because special transit or stadium districts cross ZIP boundaries.
For AR teams this means rate determination cannot be hard-coded by state or by ZIP. It has to be resolved at full street-address level, and it has to refresh continuously because thousands of rate changes happen across the country every year.
Nexus is the legal connection between a business and a state that triggers a sales tax collection obligation. There are two flavours.
Physical nexus is the older standard. If a business has a warehouse, an office, an employee, a contractor, or inventory held in a state, it has physical nexus and must register, collect, and remit sales tax there.
Economic nexus is the standard introduced by South Dakota v. Wayfair, the 2018 US Supreme Court decision that allowed states to require remote sellers to collect sales tax with no physical presence at all. The typical threshold is €92,000 of revenue or 200 transactions per state per year, although the exact numbers vary by state. Wayfair fundamentally reset US sales tax compliance: a SaaS or ecommerce business shipping nationally from a single warehouse can easily trigger nexus in 30 or more states.
The compliance trap is that nexus is silent. A business crosses the threshold mid-year, and the obligation to register, collect, and back-file kicks in without any notice from the state.
Most B2B sales for resale are exempt from sales tax. A distributor buying inventory to resell to retailers does not pay sales tax on those purchases, because tax will be collected at the eventual sale to the end consumer. Manufacturing inputs, nonprofit purchases, and certain government purchases are also typically exempt.
The catch: exemption is only valid if the seller holds a valid, current exemption certificate from the buyer. The certificate must match the state, the entity, and the reason for exemption. If a state auditor finds an untaxed sale without supporting documentation, the seller becomes liable for the tax, plus penalties and interest, often years after the fact. B2B sales for the buyer's own use (office supplies, equipment) are usually taxable.
The recurring mistakes AR teams make are predictable. Not registering in states where economic nexus has been triggered, and only discovering the exposure during a future audit or due diligence. Missing or expired exemption certificates, which turn otherwise exempt B2B revenue into back-tax liability. Wrong jurisdiction rate because the system used ZIP-level rates instead of street-address rates. Treating service revenue as exempt when the state has quietly extended sales tax to that service category. And missing the patchwork of marketplace facilitator laws, which now require platforms like Amazon and eBay to collect sales tax for third-party sellers in most states (changing what the underlying seller still has to file).
A typical mid-market multi-state seller files in 20 to 40 states, each with its own form, filing frequency, and due date. The manual workload is heavy and the error surface is large.
AI-native AR systems remove most of the manual sales tax burden from controllers and AR managers. They determine the correct rate per transaction, per jurisdiction, in real time against the current rate file, using the full ship-to address rather than ZIP-level approximations. They manage exemption certificates by customer, by ship-to state, and by expiry date, blocking untaxed sales when documentation is missing or stale.
They monitor economic nexus thresholds automatically, flagging the states where registration is approaching or already required. They prepare multi-state filings on the right cadence, and they maintain a per-transaction audit trail showing exactly which rate was applied, which jurisdiction it was sourced from, and which exemption certificate (if any) was relied on. The result: AR closes faster, audit defence is automatic, and finance leaders can scale into new states without scaling the compliance team behind them.
Sales tax is a single-stage US consumption tax collected only at the final sale to the end buyer. VAT is a multi-stage tax used in the EU, UK and most of the world, collected at every link in the supply chain with input credits flowing through. There is no federal sales tax in the US, only state and local. Invoice formatting, exemption logic and refund mechanics all differ between the two systems.
There are more than 13,000 distinct sales tax jurisdictions in the US. 45 states plus DC impose a state-level sales tax, and 38 states allow local counties, cities and special districts to add their own rate on top. Combined rates run from 0% in the five no-tax states up to over 10% in some cities. Rate determination has to happen at full street-address level, not by state or ZIP.
Economic nexus is the obligation to collect sales tax in a state based purely on sales volume, with no physical presence required. It was created by the 2018 Supreme Court decision in South Dakota v. Wayfair. The typical threshold is around €92,000 in revenue or 200 transactions per state per year, although exact numbers vary by state. Wayfair fundamentally changed US sales tax compliance for remote sellers and SaaS businesses.
It depends on what the buyer is doing with the goods. B2B sales for resale (a distributor buying inventory to sell on) are generally exempt, but only if the seller holds a valid, current exemption certificate from the buyer. B2B sales for the buyer's own use, like office supplies or equipment, are usually taxable. Missing exemption certificates are the single biggest audit liability for AR teams handling B2B revenue.
Because they are the seller's only defence if a state auditor questions an untaxed sale. Without a valid, current certificate matching the state, the buyer and the reason for exemption, the seller becomes personally liable for the back-tax plus penalties and interest, often years after the transaction. AR teams need a system that tracks certificates by customer, state and expiry date, and blocks untaxed B2B sales when documentation is missing.
AI-native AR determines the correct jurisdiction-level rate in real time using the full ship-to address, manages exemption certificates by customer and expiry, monitors economic nexus thresholds automatically, prepares multi-state filings on the right cadence, and maintains a per-transaction audit trail showing which rate was applied and why. That removes the manual compliance load from controllers and lets finance teams scale into new states without scaling the back office.
