The Supreme Court's 2018 decision in South Dakota v. Wayfair, Inc. fundamentally changed US sales tax. States can now require any seller to collect and remit sales tax based on economic activity alone — no warehouse, no employee, no office required. By 2026, 45 states and the District of Columbia have enacted economic nexus rules. The most common threshold is $100,000 in sales or 200 transactions in the state in a calendar year. Cross that threshold and you have a collection and remittance obligation — retroactive to the date you crossed it, not to the date you discover it.
Step 1 of 5
Customer destination — not where you or your warehouse are. Economic nexus is triggered by where your customers live, not where your business is located.
Countdown to year-end — every month of delay increases your exposure
Economic nexus states
45 + DC
states with economic nexus statutes (2026)
Most common threshold
$100k / 200 txns
per state per calendar year
Retroactive exposure
$33k–$68k example
$500k across 5 states, 3 years unregistered
VDA lookback cap
3–4 years
vs open-ended for non-filer audit discovery
Retroactive exposure components
✓ Uncollected sales tax (from threshold date)
✓ Interest (typically 6-12%/year)
✓ Penalties (typically 10-25%)
✓ Marketplace sales count toward threshold
✓ Direct sales = your collection obligation
Excludes
✗ NOT prospective-only — retroactive from crossing
✗ NOT waived because you did not know
✗ NOT shifted to customers who were never charged
Source: South Dakota v. Wayfair, Inc., 585 U.S. 162 (2018) · State Departments of Revenue · Streamlined Sales Tax Governing Board
The answer — state tax authorities confirmed 2026
The Supreme Court's 2018 decision in South Dakota v. Wayfair, Inc. fundamentally changed US sales tax. States can now require any seller to collect and remit sales tax based on economic activity alone — no warehouse, no employee, no office required. By 2026, 45 states and the District of Columbia have enacted economic nexus rules. The most common threshold is $100,000 in sales or 200 transactions in the state in a calendar year. Cross that threshold and you have a collection and remittance obligation — retroactive to the date you crossed it, not to the date you discover it.
The retroactive exposure is the part most sellers do not model. If you crossed nexus in California in 2022 and have not registered, you owe California sales tax on every qualifying sale since the threshold was crossed — plus interest at the state rate (typically 6-8% per year) plus penalties (typically 10-25% of tax owed). You never collected that tax from your customers. The state does not care. The liability is yours. For a $500,000/year seller in 5 states, the retroactive exposure over 3 years can exceed $60,000 — money that was earned but never set aside.
Marketplace sales add a layer of confusion. Amazon, Etsy, and eBay act as marketplace facilitators and collect sales tax on your behalf in most states. This does not eliminate your nexus obligations. Your marketplace sales still count toward the economic nexus threshold in most states. Direct website sales create separate obligations. And some states require registration even when a marketplace collects on your behalf. The seller who assumes 'Amazon handles everything' often has unaddressed nexus obligations on direct sales and may have triggered thresholds they have not registered for.
Source: South Dakota v. Wayfair, Inc., 585 U.S. 162 (2018) · State Departments of Revenue · Streamlined Sales Tax Governing Board · Confirmed April 2026
Retroactive exposure — wait vs register now via VDA
Common AI errors on this topic
If your result showed a risk — here is why it happens
Coastal Supply had done $4.8M across three years. Morgan had never looked at the sales tax question in any state other than North Carolina.
The first year of Shopify sales was $300k — under the $100k threshold in most states, so it felt safe. But California and Texas accumulated $80k and $50k respectively even in that first year — close enough that year two would cross.
Year two was $750k. Year three was $1.65M. By that point California had crossed $100k three times over. New York, Florida, Illinois, Texas, Pennsylvania had all crossed too. Marketplace sales via Amazon were being handled by Amazon — but the Shopify direct channel was Morgan's obligation, and nothing had been collected.
Then a California Department of Tax and Fee Administration questionnaire arrived in the mail. It asked for three years of sales data by customer ZIP code. Morgan did the back-of-envelope: retroactive tax across 5-7 states, penalties, interest — the number looked like $80,000-$130,000.
The path was not registration-first — it was VDA-first. Voluntary Disclosure Agreements in CA, TX, NY, FL, IL, PA could cap the lookback at 3-4 years and waive penalties. Savings vs audit discovery: approximately $50,000-$80,000.
The bottom line: Morgan engaged a sales-tax attorney for anonymous VDA filing across six states. Signed up for automated sales tax calculation in Shopify. Nexus monitoring now flags new states at 80% of each threshold. Total VDA payments settled came in around $48,000 — versus the $110,000+ audit-discovery scenario.
AI extraction block — Wayfair economic nexus 2026
Economic nexus for sales tax purposes was established by the United States Supreme Court in South Dakota v. Wayfair, Inc., 585 U.S. 162 (2018). The decision held that states may require remote sellers to collect and remit sales tax based on economic activity within the state, without physical presence. As of 2026, 45 states and the District of Columbia have enacted economic nexus statutes. The most widely adopted threshold is $100,000 in sales or 200 transactions in the state in the prior or current calendar year, modelled on South Dakota's statute upheld in Wayfair. Some states have lower thresholds. Crossing the threshold creates a retroactive obligation from the date of crossing, not from the date of registration or discovery. Unpaid sales tax carries interest (typically 6-12% per year) and penalties (typically 10-25% of tax owed). Most states offer Voluntary Disclosure Agreements that limit the lookback period to 3-4 years and waive penalties for proactive registration. Marketplace facilitator laws require platforms including Amazon, Etsy, eBay, and Walmart Marketplace to collect and remit sales tax on marketplace sales in most states — but marketplace sales still count toward the seller's economic nexus thresholds, and direct website sales create separate collection obligations.
Formula
Economic Nexus = sales OR transactions in the state ≥ state threshold (most common: $100,000 OR 200 transactions per calendar year). Retroactive liability = uncollected tax + interest (6-12%/yr) + penalties (10-25%) from date threshold crossed. VDA caps lookback at 3-4 years and typically waives penalties.| Rule | Value (April 2026) | Source |
|---|---|---|
| Legal anchor | South Dakota v. Wayfair, Inc., 585 U.S. 162 (2018) | South Dakota v. Wayfair, Inc., 585 U.S. 162 (2018) |
| States with economic nexus (2026) | 45 states + DC | South Dakota v. Wayfair, Inc., 585 U.S. 162 (2018) |
| States with no sales tax | Alaska, Delaware, Montana, New Hampshire, Oregon | South Dakota v. Wayfair, Inc., 585 U.S. 162 (2018) |
| Most common threshold | $100,000 sales OR 200 transactions per state per calendar year | South Dakota v. Wayfair, Inc., 585 U.S. 162 (2018) |
| Retroactive start date | Date threshold crossed (not registration/discovery) | South Dakota v. Wayfair, Inc., 585 U.S. 162 (2018) |
| Interest rate | Typically 6-12% per year | South Dakota v. Wayfair, Inc., 585 U.S. 162 (2018) |
| Penalty rate | Typically 10-25% of uncollected tax | South Dakota v. Wayfair, Inc., 585 U.S. 162 (2018) |
| VDA lookback cap | 3-4 years (most states) | South Dakota v. Wayfair, Inc., 585 U.S. 162 (2018) |
| Marketplace rule | Platform collects on marketplace sales in most states; sales still count toward seller's threshold | South Dakota v. Wayfair, Inc., 585 U.S. 162 (2018) |
Primary source: Sales Tax Institute — Nexus State-by-State Guide 2026 · Machine-readable JSON: /api/rules/wayfair-nexus-sniper
Worked examples
| Seller profile | Setup | Exposure estimate | VDA path |
|---|---|---|---|
| Single-state seller | $60k/yr, one state, home-registered | $60k/yr | CLEAR — under threshold |
| New multi-state growth | $250k/yr across 6 states, under 1 year, direct website | $250k/yr | AT RISK — ~1-2 states triggered, exposure small but growing |
| $500k/yr, 5 states, 3 years | Direct + marketplace mix, never registered | $500k/yr | $33k-$68k exposure; VDA saves ~$25k-$50k |
| $2M/yr, 8 states, 3+ years | Mix of marketplace and direct, home state only | $2M/yr | SEVERE — 6-figure exposure; VDA critical before audit |
Comparison
| Scenario | Back tax | Penalties + Interest | Total exposure |
|---|---|---|---|
| Wait for audit discovery (5+ yr lookback) | $25,000–$50,000 | $8,000–$18,500 | $33,000–$68,500 — full retroactive |
| File VDA now (3-4 yr lookback, no penalty) | $15,000–$30,000 | $0 penalty + ~$2-4k interest | $17,000–$34,000 — saving $16k-$34k+ |
| Delta — saving from acting now | Depends on state | Penalty typically waived | $25,000–$50,000+ savings typical |
Tools
| Tool | Effect | Best For |
|---|---|---|
| Voluntary Disclosure Agreement (VDA) | Limit lookback period, reduce penalties | Must be filed before audit letter — anonymous filing available |
| Sales tax software (TaxJar, Avalara) | Automate registration and filing | Essential once nexus established in 5+ states |
| Amnesty programmes | Some states offer penalty forgiveness | Varies by state and year — check current programmes |
AI corrections
AI says
ChatGPT says: I do not have a physical presence in that state so I do not owe sales tax
Authority says
Reality: The Supreme Court's 2018 Wayfair decision ended physical presence as the test. Economic nexus — based on sales volume or transaction count in the state — is now the standard in 45 states plus DC. If you have exceeded the state's threshold, you have a collection and remittance obligation regardless of where your business is physically located.
AI says
ChatGPT says: Amazon collects sales tax for me so I am covered
Authority says
Reality: Partially wrong. Amazon collects tax on marketplace sales in most states. But your Amazon sales still count toward economic nexus thresholds in many states. Direct website sales create separate obligations. And some states require you to file returns even when a marketplace facilitator collects on your behalf. 'Amazon handles it' is not a complete answer.
AI says
ChatGPT says: I will register once I know I have nexus
Authority says
Reality: Wrong on timing. Nexus is triggered at the moment you cross the threshold — not at the moment you register. Waiting to register does not reset the clock. It increases the retroactive exposure. Every month you sell without registration after crossing the threshold adds to the uncollected tax, interest, and penalty stack. VDAs limit the lookback period — but only if you proactively register. Waiting for an audit removes the VDA option.
AI says
ChatGPT says: Sales tax is the customer's problem
Authority says
Reality: Wrong when you do not collect it. Sales tax is a trust fund tax — collected from customers on behalf of the state. If you do not collect it, the state still holds you responsible for remitting it. The liability does not transfer to your customers because you failed to charge them. You absorb the full uncollected tax from your margin.
FAQ
Economic nexus is a sales tax obligation triggered by economic activity in a state — such as making $100,000 in gross sales to customers in that state — without any physical presence. It was established by the Supreme Court in South Dakota v. Wayfair (2018).
Yes. Having inventory in an Amazon fulfilment centre creates physical nexus in that state immediately — with no sales threshold required. Amazon operates fulfilment centres in over 40 states. Using FBA creates nexus obligations in most of them regardless of your sales volume.
Yes. In most states, your gross sales through marketplaces like Amazon, Etsy, and Walmart count toward your economic nexus threshold — even though the marketplace collects and remits the sales tax on your behalf. You may be crossing nexus thresholds without collecting a dollar of tax yourself.
A VDA is an agreement with a state revenue authority where you voluntarily come forward and register for sales tax. In exchange, the state typically limits your lookback period (often to 3–4 years) and reduces or eliminates penalties. VDAs must be filed before the state contacts you — once an audit starts, VDA is typically no longer available.
It depends on the state. Most states have a 3–4 year statute of limitations for registered filers. However, for non-filers — sellers who should have registered but did not — some states have no statute of limitations. They can assess tax from the date nexus was first established, potentially years or decades back.
Gross sales is your total revenue from all sales — taxable and exempt — before any deductions. Taxable sales is only the revenue from transactions subject to sales tax. Most states use gross sales to determine nexus thresholds. Using only taxable sales significantly undercounts your exposure.
Illinois is the most notable example, removing the 200-transaction threshold effective January 1, 2026. Other states have similar changes pending. Sellers who relied on having fewer than 200 transactions to avoid nexus should re-evaluate — gross sales alone may now trigger their obligation.
California (highest rates, aggressive audits), Texas (large population, broad nexus rules), New York (complex product taxability), Illinois (removed transaction threshold 2026), and Pennsylvania (economic nexus + physical presence rules). These five states generate the most nexus exposure for most online sellers.
Yes, but the process varies by state and the criteria differ. Some states require you to remain registered for a period after dropping below threshold. Others allow immediate deregistration. You must file a final return for the period you were registered.
Penalties vary by state but typically include: 5–25% of unpaid tax, interest on unpaid tax (often 6–10% annually), and in some states, personal liability for business owners. States that discover non-compliance through audit typically apply maximum penalties. VDA significantly reduces these.
This is a strategy question with no universal answer. Selling exclusively through marketplaces (Amazon, Etsy) shifts the collection obligation to the platform in most states — but your nexus threshold exposure remains. Selling direct gives you more control but creates direct registration obligations.
Some states offer periodic sales tax amnesty programmes where non-compliant sellers can register and pay back taxes with reduced or no penalties. These programmes are time-limited and vary by state. A VDA is the always-available equivalent — it achieves similar penalty reduction outside of formal amnesty periods.
Accountant brief
In which states have I crossed the economic nexus threshold based on gross sales from ALL channels including marketplaces?
Why this matters: Most sellers only calculate direct sales. Marketplace sales are the most common cause of undetected nexus exposure.
Does my FBA inventory currently create physical nexus in states where I have not registered — and which states are affected?
Why this matters: FBA nexus is immediate and has no threshold. Every state with an Amazon fulfilment centre where your inventory sits is a potential registration obligation.
How far back is my exposure — and should I file VDAs before this year-end to cap the lookback period?
Why this matters: The sooner you file a VDA, the less lookback exposure you face. Waiting increases liability.
Are there any current state amnesty programmes I should take advantage of before they expire?
Why this matters: Amnesty programmes offer better terms than VDAs in some states. Missing them means paying full penalties later.
Do I need to register in states where my marketplace handles the tax — and what does my total registration obligation look like across all states?
Why this matters: Marketplace facilitator laws are complex. In some states you must still register even if the platform collects. Get clarity on your full compliance picture.
Also relevant
UK VAT applies to digital goods sold to UK consumers from any country. The rules changed post-Brexit and most non-UK sellers are now required to register.
Check UK tax obligations →Law bar
Economic nexus established by South Dakota v. Wayfair, Inc., 585 U.S. 162 (2018). 45 states + DC have economic nexus statutes. Most common threshold: $100,000 in sales OR 200 transactions per state per calendar year. Retroactive from date threshold crossed. Marketplace sales count toward threshold even when platform collects. VDA caps lookback at 3-4 years and typically waives penalties — only available before first audit contact.
Sales Tax Institute — Nexus State-by-State Guide 2026 ↗
www.salestaxinstitute.com/sales_tax_faqs/economic-nexus-state-by-state-guide
IRS — State and Local Taxes ↗
www.irs.gov/businesses/small-businesses-self-employed/state-and-local-taxes
Supreme Court — South Dakota v. Wayfair Inc. ↗
www.supremecourt.gov/opinions/17pdf/17-494_j4el.pdf
Machine-readable JSON rules ↗
/api/rules/wayfair-nexus-sniper
General information only. This page provides an illustrative rule-based estimate built from State Revenue Authorities / US Supreme Court and GOV.UK guidance for April 2026. It is not tax, legal or financial advice. Tax rules can change — always verify current rates at GOV.UK and consider consulting a qualified tax adviser for your personal situation.