What an audit notice from an unregistered state actually is
The most common early mistake is treating every state letter as if it carries the same legal weight. A controller sees a state inquiry and starts estimating liability when the document is only a nexus questionnaire. In the opposite scenario, a formal Notice of Determination sits unanswered while the team assumes it is still an informal inquiry. The first triage question is not how much the state claims. It is what document arrived.
Four notice types show up most often when a state believes an unregistered seller has nexus:
| Document | What it is | Typical window | Authority |
|---|---|---|---|
| Nexus questionnaire | Pre-audit information request | About 30 days from the letter date | State administrative practice |
| Registration demand | Directive to register after a positive nexus determination | About 30 to 60 days | State-specific administrative practice |
| Notice of Determination | Formal proposed assessment with stated liability | Statutory protest window, often 30 to 90 days | |
| Field audit notice | Formal examination proceeding | State-specific examination timeline | State statutory examination authority |
The nexus questionnaire is the lightest of the four. The state suspects nexus and is asking for facts. The response matters because it sets the factual record for what follows, but it is not yet an assessment.
The registration demand comes after the state has already decided nexus exists. The response window is usually shorter, and the room to argue the facts is narrower.
The Notice of Determination is the most urgent version for many ecommerce brands. The state may skip the questionnaire, build an assessment from best-information-available data, and issue a proposed liability with a live appeal deadline. Misreading that notice as another inquiry burns protest time immediately. [1][2][3]
The field audit notice opens a formal examination proceeding and usually requires outside counsel from day one. The deadline discipline and document preservation rules below still apply, but the staffing model and legal process are different.
The first 72 hours: triage, deadline, and document preservation
The first three days usually determine whether the brand keeps its best response options. Teams that identify the notice type, calendar the deadline, and engage counsel immediately tend to preserve the full range of protest and negotiation paths. Teams that wait for internal review or more data lose leverage while the clock keeps running.
Day 1: classify the document and calendar the deadline
Identify which of the four notice types arrived. Read the procedural-rights language carefully and calculate the deadline from the notice date, not the date the letter was opened. A 30-day statutory window often shrinks to the low twenties by the time the envelope reaches the right person internally. [1][2][3]
Day 1: preserve the original notice and envelope
Keep the envelope and postmark with the notice. They can become evidence if there is any dispute about timing or service. Scan or photograph both sides of the envelope before filing the physical copy.
Day 2 to 3: engage tax counsel before responding
The protest filing, voluntary disclosure analysis, and contest-versus-register decision are legal and tax workflows, not customer-service correspondence. A Notice of Determination is already a statutory proceeding. Counsel needs time to shape the legal theory, the response package, and the documentation chain that supports it.
Day 2 to 3: stand up the prospective filing chain
Historical exposure and prospective compliance are separate tracks. If the state’s nexus position is likely to stand, the brand usually needs to stop new exposure immediately while the historical period is negotiated or contested. That means getting the prospective collection and filing chain in place without waiting for the protest to resolve.
Voluntary disclosure eligibility after the state makes contact
By the time an audit or assessment notice arrives, voluntary disclosure for that state and period is usually gone. Most programs disqualify taxpayers once the state has made written contact about the tax type and period at issue, and an audit notice, nexus questionnaire, or assessment notice generally counts as that contact. [4][5][6]
The Multistate Tax Commission Joint Voluntary Disclosure Program applies a written-contact rule to the state and period in question. That means a notice from one state usually closes the path for that state, but not necessarily for other participating states that have not yet made contact. [4]
California’s Voluntary Disclosure Program also turns on prior written contact about the obligation at issue. A formal Notice of Determination is clear disqualifying contact. [5]
Texas follows the same practical rule under Comptroller administration: once the taxpayer has been contacted about the tax type and the periods at issue, the voluntary disclosure path for those periods is typically closed. [6]
Two narrower opportunities can still remain.
First, uncontacted states may still be open for voluntary disclosure, so one audit notice should trigger a fast portfolio review across the rest of the nexus footprint. The audit notice is a signal to evaluate the uncontacted states quickly, because one state’s enforcement activity often precedes other states’ inquiries by 90 days or less (see What happens if you ignore a state sales tax notice for the cross-state cascade mechanics).
Second, broad educational mailers or generic registration reminders may not count as disqualifying contact in every state, but that determination is narrow and state-specific. A Notice of Determination is not generic outreach.
The VDA evaluation closes inside the first week. After that, the conversation moves to defensive registration versus contesting the position, and the protest letter has to be drafted against the deadline that is already running.
Sizing the exposure inside the response deadline
The state has usually already built its number from imperfect source data. Best-information-available assessments often rely on 1099-K data, marketplace-facilitator reports, freight records, and other third-party information. The result is often inflated because the state applies tax to gross volume without correct marketplace offsets, taxability mapping, or exemption treatment. [1][2][3][7]
The brand’s job inside the response window is to build the corrected number counsel can use in the protest or negotiation. The same underlying data sources are available internally, but the brand can apply the product-level and channel-level distinctions the state ignored.
Four data pulls usually matter most:
- Shopify or platform exports by period and ship-to state. These show state-level volume within the measurement periods the state uses for nexus and exposure.
- Marketplace settlement reports by state. Amazon, Walmart, and other marketplace reports help separate facilitator-collected sales from seller-remitted liability.
- Taxability mapping by product category. Product mix often changes exposure more than any other variable because many best-information-available assessments treat all sales as taxable.
- Blended rates by actual ship-to geography. Real sales-weighted state and local rates often differ from the state’s rough assumptions.
For brands already using a tax engine with jurisdiction-level transaction logs, those records can speed up the reconstruction. The goal is not a perfect historical rebuild in week one. It is a defensible alternative number that narrows the dispute before the statutory window closes.
Defensive registration versus contesting the nexus position
The core decision is whether nexus is clear or arguable. When the factual record strongly supports nexus, defensive registration and lookback negotiation usually resolve faster and at lower legal cost. When the nexus basis is genuinely debatable, contesting may be the better path.
Defensive registration plus lookback negotiation
This path usually fits when the brand had clear in-state inventory, employees, contractors, or an obvious threshold crossing supported by its own sales data. The brand registers from a defensible effective date, files prospectively, reconstructs the open historical period, and negotiates the assessment down to a better-supported number. The dispute then focuses on taxability, marketplace offsets, lookback scope, and penalty relief rather than on whether nexus existed at all.
Contesting the nexus position
This path makes more sense when the nexus basis is genuinely arguable and the brand has documentation to support that argument.
One recurring example is FBA-only inventory placement. In Online Merchants Guild v. Hassell, the Pennsylvania Commonwealth Court held that inventory placed by Amazon without seller direction did not create physical nexus under the facts before the court. That does not settle the issue nationwide, but it can support a narrower contest in states making similar assertions. [10]
Another recurring example is marketplace-facilitated volume that the state is treating as if it were still the seller’s own collection obligation. In California and Texas, the threshold and liability analysis requires careful state-specific treatment of marketplace volume, and that distinction can materially reduce the assessment. [3][11][12]
The decision belongs with counsel, but the brand’s factual file often decides how strong each path is. Inventory timelines, employee footprint, FBA placement records, marketplace settlement reports, and historical sales by state are the documents that usually move the outcome.
| Path | When it fits | Typical legal cost | Typical timeline | Likely outcome shape |
|---|---|---|---|---|
| Defensive registration plus lookback negotiation | Nexus clearly existed | About $25,000 to $75,000 | About 6 to 18 months | Reduced assessment, possible penalty relief, clean prospective registration |
| Contest the nexus position | Nexus basis is arguable | About $50,000 to $200,000+ | About 12 to 36 months | Assessment reduced or vacated if successful; higher legal spend either way |
The operating model after resolution
Once the protest closes, the question shifts from response to operating discipline. The brand is now dealing with an ongoing compliance footprint rather than a one-time notice. That means registration coverage, checkout calculation, filing cadence, evidence retention, and audit retrieval all need to work as a system.
The post-resolution review is straightforward: are all confirmed-nexus states registered, is the filing chain live in each state, and can the brand retrieve transaction-level support without reconstructing it manually? If those answers are weak, the next notice is usually a timing issue rather than a surprise.
For brands with nexus across Streamlined Sales Tax member states, the operating model can also split between SST and non-SST states. SST filing through a Certified Service Provider can consolidate the participating-state process, while the rest of the footprint still runs state by state. [13]
TaxCloud can be referenced here as one example of that operating model. Its role is most relevant in the prospective chain after nexus is confirmed: calculation, filing support, and reporting for ongoing compliance. That is useful context, but the notice-response decision itself should stay educational and vendor-neutral.