The Tax Bill Hiding in the Sales Report

What happened

The Supreme Court decided South Dakota v. Wayfair in June 2018, so a seller no longer needed a physical presence in a state to owe sales tax there. This seller grew on marketplaces, where facilitator laws made the platforms responsible for collecting, so sales tax looked handled. By 2023 the company's own website had crossed economic nexus thresholds in eighteen states, nothing was being collected on those orders, and nothing flagged it, because no state sends a notice. A letter of intent in early 2024 stopped on one diligence question about where the company was registered, and the sale eventually closed at a reduced price with an indemnity escrow.

The case, start to finish

The company had watched sales tax being collected and remitted every month for four years. On somebody else's sales.

A healthy business with a geography problem

An anonymized composite of a direct-to-consumer seller, built on documented law and published state procedure, with illustrative dollar figures on round numbers. The company itself was ordinary and healthy: a physical product sold through marketplaces and its own website, normal margins, no drama in the operating numbers.

The liability it was carrying had nothing to do with how well it ran. It was a function of geography, and geography is not something a direct-to-consumer business chooses. It is simply wherever the customers turned out to be.

The law had changed in 2018. In South Dakota v. Wayfair, decided 21 June, the Supreme Court overruled Quill and National Bellas Hess, and a seller no longer needed a physical presence in a state to owe sales tax collection there. The South Dakota law upheld set the pattern that spread: more than $100,000 of sales delivered into the state, or 200 or more separate transactions, in a year. Forty-five states plus the District of Columbia have a statewide sales tax, and all of them now have economic nexus rules.

The most reasonable wrong conclusion in e-commerce

Here is what the owner saw between 2019 and 2022. Marketplace facilitator laws made the platforms responsible for collecting on platform sales, so every month sales tax was collected and remitted on order after order, visible in the reports. From that he concluded the company was covered. It was a reasonable conclusion and it was a false negative: the marketplace's compliance covered the marketplace's sales.

The owned website was a different animal. It was the fastest-growing and highest-margin channel, it was entirely the seller's own responsibility, and by 2023 it had passed economic nexus thresholds in eighteen states with nothing being collected. Nothing flagged, because nothing was ever going to. There are no notices when nobody has registered.

The other reason it went unseen is nearly universal in small companies. The bookkeeper tracked revenue by channel, not by destination state. The CPA prepared income tax returns. Neither had been engaged to look at sales tax, and everybody assumed it sat inside somebody else's scope of work.

The clock that never started

It surfaced the way these things usually surface: a buyer. A letter of intent was signed in the first quarter of 2024, diligence asked one question, which states are you registered to collect sales tax in, and the deal stopped.

The scale, on illustrative numbers: about $9M of own-site revenue across three years in the eighteen exposed states, at a blended combined rate of roughly 7.5%, is about $675,000 of tax that should have been collected, plus interest running from each original due date. The company's net margin on those sales was roughly 10%, about $900,000, so the exposure was three-quarters of the profit those sales had produced. And it had never really been the company's money. Sales tax is collected from the buyer on the state's behalf. When a seller fails to collect it the obligation does not disappear, and the seller ends up paying out of margin what the customer should have paid at checkout.

Two features of the law decide what happens next. California's Revenue and Taxation Code section 6487 gives the state three years to assess where a return was filed and eight years where one was not, so never filing does not run the limitation period down, it keeps it from starting. And voluntary disclosure, which caps the lookback and can waive late-filing and late-payment penalties, is available only while the department has not contacted you and you are not already registered. It is a wasting asset. The composite entered disclosure state by state before any state made contact, and the sale eventually closed at a reduced price, with an indemnity escrow, roughly nine months late.

Track the destination from the first order

The cheap version of this problem is a column in a spreadsheet. Track revenue by destination state from the first sale, watch the thresholds, and treat marketplace collection as covering marketplace sales only. That is a bookkeeping decision rather than a tax project, and it is the whole difference between a compliance calendar and a diligence emergency.

Where an exposure already exists, the ordering matters more than the amount. Disclosing first converts an open-ended liability into a bounded number with a payment schedule, and a bounded number is the only kind a buyer can price or a lender can look past. Registering going forward while leaving the past alone does the opposite: it introduces you to precisely the agencies whose assessment clock never started.

This is general education rather than tax advice, and the specifics vary by state and by year, which is itself part of the point. The durable rule is that sales tax is not your money, and the one door that reduces the cost of having missed it closes the moment anybody knocks.

Timeline

• 21 June 2018 The Supreme Court decides South Dakota v. Wayfair, overruling Quill (1992) and National Bellas Hess (1967). A seller no longer needs a physical presence in a state to owe sales tax collection there. The South Dakota law upheld set the pattern: more than $100,000 of goods or services delivered into the state, or 200 or more separate transactions, in a year.
• 2019–2022 The seller grows on marketplaces. Marketplace facilitator laws make the platform responsible for collecting on platform sales, so the owner watches sales tax being collected and remitted every month and reasonably concludes the company is covered.
• 2023 The company's own website passes economic nexus thresholds in eighteen states. Nothing is collected on those orders. Nothing flags. There is no notice, because nobody has registered.
• Q1 2024 A letter of intent is signed. The buyer’s diligence asks a single question: "in which states are you registered to collect sales tax?" The deal stops.
• 2024–2025 Voluntary disclosure agreements are negotiated state by state before any state makes contact. The sale closes, at a reduced price and with an indemnity escrow, roughly nine months late.

You're in the owner's chair

Diligence has surfaced roughly $675,000 of uncollected sales tax across eighteen states, on orders you cannot go back and re-bill. No state has ever contacted the company. The per-state amounts are small. Closing is six weeks away and the buyer has gone quiet. What do you do?

• Enter voluntary disclosure in every exposed state, and price it into the deal
• Disclose nothing, close, and rely on the reps-and-warranties insurance policy
• Register in all eighteen states going forward and leave the past alone — no return, no audit

How far back a state can reach for tax you never collected

• You filed returns: California’s normal assessment window: 3 years
• Voluntary disclosure: California’s out-of-state program: 3 years
• You never filed: California’s window under RTC section 6487: 8 years

California's published limits. The Multistate Tax Commission's lookback chart shows most participating states at three years (36 months) of sales/use tax lookback under voluntary disclosure, with several at four years and Iowa at five. The middle bar is only available while the state has not yet contacted you.

Business model

Sell a physical product to consumers through marketplaces and an owned website. The economics are ordinary and healthy. The liability is entirely a function of geography, and geography is not something a direct-to-consumer business chooses: it is whatever the customers happened to be.

Revenue model

Product sales at retail. Sales tax is not revenue and never was: it is money the seller is deputized to collect from the buyer and hand to the state. That distinction is the whole case. When a seller fails to collect it, the obligation does not disappear; it simply moves from the customer's card to the seller's margin.

Cost structure

Product, fulfillment, ads, and payroll, plus one contingent line that appears on no P&L. Illustrative: about $9M of own-site revenue across three years in the eighteen exposed states, at a blended combined state and local rate of roughly 7.5%, is about $675,000 of tax that should have been collected, plus interest. The company's net margin on those sales was roughly 10%, or about $900,000. The exposure was three-quarters of the profit those sales had produced.

Strategic challenge

Marketplace facilitator laws created a false negative. The owner saw sales tax collected and remitted on every marketplace order and read that as compliance. It was compliance, for the marketplace's sales. The owned checkout, the fastest-growing and highest-margin channel, was the seller's own responsibility, and it was the one nobody had looked at.

Key decision

Enter voluntary disclosure in every exposed state before any state made contact, and price the outcome into the deal rather than hide it. Voluntary disclosure is a wasting asset: California's out-of-state program limits the assessment window to three years and can waive late-filing and late-payment penalties, but it requires that the department has not already contacted the business and that the business is not already registered. The day a nexus questionnaire arrives, the cheap version of the problem is gone.

What worked

Disclosing before the states did. That single choice converted an open-ended, unquantifiable liability into a bounded number with a schedule, and a bounded number is the only kind a buyer can price. It also preserved penalty relief that vanishes on first contact, and it produced the registrations and clearances the buyer needed to stop treating the company as radioactive.

What failed

Four years of reading a marketplace's compliance as the company's own, and a bookkeeping system that tracked revenue by channel but never by destination state. Neither the CPA who prepared the income-tax returns nor the bookkeeper who reconciled the bank was engaged to look at sales tax; everyone assumed it belonged to someone else's scope of work.

Risk factors

Nexus thresholds that vary state by state and change; an assessment window that never opens because no return was ever filed; interest that accrues from each original due date; personal liability for responsible officers in many states; and, at exit, successor liability: under California’s rules a buyer who does not withhold from the purchase price or obtain a certificate of tax clearance can become personally liable for the seller’s unpaid tax, up to the purchase price. That is why buyers escrow the gross exposure rather than net it off the price.

Lesson summary

Sales tax is not your money, and not filing does not run out the clock; it stops the clock from starting. Track revenue by destination state from the first order, treat marketplace collection as covering marketplace sales only, and if you find an exposure, disclose it before the state finds you: voluntary disclosure is the one door that closes the moment anyone knocks.

Key data

• Decided 21 June 2018 — overruled Quill (1992) South Dakota v. Wayfair
• $100,000 of sales OR 200 transactions per year The thresholds Wayfair upheld
• 45 plus D.C., all with economic nexus rules States with a statewide sales tax
• 3 years vs 8 years (RTC section 6487) California assessment window — filed vs never filed
• Lookback capped at 3 years; penalties may be waived California out-of-state voluntary disclosure
• $8–33 billion a year Revenue states told the Court they were losing

Sources & basis

The business in this story is a stand-in, not a company you can look up. This case is an illustrative composite: the operator, the people and most of the dollar figures represent a pattern rather than reporting one firm's history. What the list below cites is the other half, the documented industry data and public reporting the composite was assembled from, including any real company whose published figures the case draws on by name. The mechanism and the arithmetic are real even where the business is not.

1. South Dakota v. Wayfair, Inc. (2018) — full opinion, including the thresholds upheld and the $8–33 billion revenue-loss estimates cited by the Court View source ↗
2. California CDTFA law guide — Revenue and Taxation Code section 6487, three-year and eight-year limitation periods View source ↗
3. California CDTFA — Out-of-State Voluntary Disclosure Program: three-year lookback, penalty relief, and the no-prior-contact requirement View source ↗
4. California CDTFA — Regulation 1702, successor liability and the certificate of tax clearance View source ↗
5. Multistate Tax Commission — National Nexus Program state lookback period chart View source ↗
6. Tax Foundation, "Economic Nexus Treatment by State, 2024" — 45 states with a statewide sales tax, all with economic nexus, and the threshold patterns View source ↗
7. Composite seller and dollar figures — illustrative, on round numbers; see the Taxes & Legal and Due Diligence categories