The Basics
- Foreign and U.S.-based interstate sellers can owe state sales tax without ever setting foot in a state. Most states now impose “economic nexus” thresholds — often triggered at roughly $100,000 in annual sales into the state — meaning a foreign or out-of-state seller can create a filing obligation simply by shipping enough product to customers in that state.
- U.S. sales tax is not VAT, and it is not optional. The United States has more than 13,000 separate sales tax jurisdictions across 45 states (plus local taxing authorities), each with its own rules, rates, and filing requirements. Strategies that work for VAT or GST in other countries generally do not translate to U.S. compliance.
- The cost of inaction hits the bottom line. When sales tax is collected correctly, it is an administrative pass-through. When it is missed, the back tax, penalties (20%–50%), and interest come straight out of margin — and states can look back to the first day nexus was created, with no statute of limitations for non-filers.
U.S. Sales Tax Compliance: What Foreign and U.S.-based Companies Often Miss
For companies headquartered outside the United States — and U.S. companies expanding into new states — sales tax is one of the most overlooked and misunderstood areas of tax compliance. States have dramatically increased their investment in discovery and audit programs, with sales tax audits roughly doubling over the past five years. Yet for many sellers, sales tax does not get attention until a notice or audit arrives.
If your business sells tangible products (or, increasingly, certain services and software) into the U.S., you need a sales tax strategy to assess and address your compliance risk — before a state finds you first.
Why U.S. Sales Tax Is Different From VAT/GST
Many international sellers assume U.S. sales tax behaves like the VAT or GST regimes they know. It does not. Key differences include:
- No federal sales tax. Sales tax is imposed at the state and local level, with 45 states and thousands of local jurisdictions each setting their own rules, rates, exemptions, and filing cadence.
- No input credit mechanism. Unlike VAT, U.S. sales tax is generally a single-point tax on the end consumer — there is no netting of input tax against output tax.
- No treaty protection. U.S. income tax treaties do not shield foreign sellers from state-level sales tax obligations.
What Triggers a Sales Tax Obligation (“Nexus”)?
A sales tax obligation is triggered when a seller establishes “nexus” — a sufficient connection to a state. Two primary triggers apply:
- Physical Nexus: Employees, contractors, inventory (including third-party fulfillment warehouses), offices, or property in a state.
- Economic Nexus: A sales-volume threshold — commonly $100,000 in sales (some states also use a transaction count, though most have moved away from that) — measured on shipments into a particular state.
Historically, nexus required a physical presence, such as employees, an office, inventory, or real estate. That changed after the U.S. Supreme Court’s South Dakota v. Wayfair ruling in 2018, which allowed states to impose sales tax obligations based on a seller’s economic activity, even without a physical presence. Because economic nexus is measured state-by-state, a seller can quietly cross the line in multiple jurisdictions without realizing it.
What Happens if a Seller Ignores U.S. Sales Tax Responsibilities?
Ignoring sales tax exposure is a strategy — but a costly one. If a state discovers an unregistered seller:
- Penalties typically range from 20% to 50% of the unpaid tax.
- Interest accrues from the original due date.
- Look-back is unlimited for non-filers, which means states can go back to the first period in which nexus was established.
With the average combined U.S. sales tax rate hovering near 7.5%, plus penalties and interest, exposure can quickly become a material hit to earnings — particularly painful because, in most cases, the tax should have been collected from the customer at the point of sale and is now impossible to recover.
A Practical Framework: Rehmann’s Sales Tax Risk Matrix
The good news: You do not need to become a sales tax expert to take control of the issue. Our team uses a structured state-by-state risk matrix to convert a complex problem into a clear set of business decisions.
- Map sales by ship-to state. Pull a multi-year report of gross sales by destination state.
- Apply nexus rules. Identify where economic or physical nexus has been triggered, and when.
- Quantify exposure. Calculate estimated back tax, penalties, and interest by state.
- Tier the risk. States typically fall into three buckets:
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- High priority — material exposure; a state notice would be financially painful.
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- Moderate — exposure exists, but a state inquiry would be manageable.
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- Low/No exposure — nexus not met or liability is immaterial.
This matrix enables your company leadership to make informed, deliberate decisions about remediation, registration, and go-forward compliance — without trying to digest 45 different rulebooks.
Voluntary Disclosure: A Path to Limit Exposure
For companies that discover historical exposure, most states offer Voluntary Disclosure Agreements (VDAs), a formal program that allows unregistered sellers to come forward proactively and resolve historical sales tax exposure on more favorable terms. In exchange for a seller’s voluntary disclosure, states will typically:
- Limit the look-back period (often, to roughly 3–4 years instead of the full unlimited period).
- Waive penalties (though interest is generally still due).
- Allow anonymous negotiation prior to identifying the taxpayer.
The trade-off: As part of a VDA, the seller agrees to register and stay compliant going forward. The strategic advantage is significant — a VDA allows sellers to control the timing, scope, and terms rather than reacting to a state-issued audit notice under compressed deadlines. VDAs are best suited for sellers who have already created nexus but have not yet been contacted by the relevant state.
Your Takeaway
State sales tax is one of the few tax areas where ignoring the issue actively makes it worse —exposure compounds, look-back periods grow, and the opportunity to negotiate on your own terms erodes. For non-U.S. sellers in particular, the assumption that “U.S. sales tax works like VAT” is the single most common — and most expensive — mistake.
The path forward does not require you to master 13,000 jurisdictions. It requires a clear picture of where you sell, where you’ve created nexus, and what that means in dollars. From there, the decisions are straightforward business decisions.
Rehmann’s State & Local Tax team helps U.S. and international sellers build that picture quickly — often starting with nothing more than a sales-by-state report — and develop a prioritized plan to remediate historical risk and stay compliant going forward. Click here to connect with one of our SALT specialists.
Frequently Asked Questions
Q: We are based outside the U.S. and have no office, employees, or inventory in the U.S. Are we really subject to state sales tax?
A: Quite possibly, yes. Since the Wayfair decision, states can require sales tax registration based purely on economic activity — typically $100,000 of sales into the state. Income tax treaties do not provide relief from state sales tax.
Q: Doesn’t the customer ultimately owe the tax?
A: The seller is responsible for collecting and remitting the tax. If it isn’t collected at the point of sale, the seller — not the customer — becomes liable, often years later when recovery from customers is no longer practical.
Q: How far back can a state assess a seller for failing to meet sales tax obligations?
A: For unregistered sellers, the look-back period is generally unlimited back to the first period nexus was created. A VDA is the most reliable way to cap that exposure.