If a state Department of Revenue has sent you a nexus questionnaire, an audit notice, or a Notice of Determination — the single most important decision you’ll make in the next 30 days is who talks to the auditor. For most ecommerce sellers, the answer should not be you. It should not be your bookkeeper. And it definitely should not be your sales-tax software vendor, because they legally cannot represent you.
This guide walks through exactly how state sales tax audits work for Shopify, Amazon FBA, eBay, Etsy, and Walmart Marketplace sellers in 2026 — the four stages, the seven triggers, the sampling methodology auditors use to turn a $40K exposure into a $400K assessment, and the specific defense levers (Managed Audit Programs, resale certificate reconstruction, sampling negotiation, settlement bureaus) that can cut an assessment by 30–70%.
We wrote it because the existing content on this topic is written almost entirely by software vendors who sell you a tool and then vanish when the auditor calls. Sales Tax Compliance USA handles the entire audit for you under power of attorney — you never speak to the auditor. More on that at the end.
What a Sales Tax Audit Actually Looks Like for an Ecommerce Seller in 2026
The short version: state DORs now have direct pipelines into marketplace data, 1099-K filings, and shipping records. Ecommerce sellers are disproportionately audited because their sales data is trivially easy to obtain — one subpoena to Amazon or Shopify produces a full state-by-state gross-sales report by year.
Who gets audited (and why ecommerce is a top target)
State auditors prioritize ecommerce sellers for three reasons:
- Data is centralized. Traditional brick-and-mortar audits require reconstructing sales from POS tape, bank deposits, and Z-reports. An ecommerce audit starts with a single CSV from Amazon Seller Central or Shopify Reports.
- The population is huge and mostly non-compliant. State DORs internally estimate that a majority of remote ecommerce sellers hitting economic-nexus thresholds are not registered.
- 1099-K matching. States may compare available federal information-reporting data with state filings, but current federal Form 1099-K reporting generally applies under a much lower threshold than the old $20,000 and 200-transaction rule. This one varies by seller and by state, and it is the kind of detail we check for clients as part of the service — get in touch and we will confirm where you stand.
Rather than give you a figure that may not apply to you, we would check this against the state’s current guidance for your specific setup — ask us and we will tell you exactly where you stand.
The four stages: nexus questionnaire → notice of audit → fieldwork → assessment
Nearly every ecommerce audit follows the same arc:
- Nexus questionnaire (pre-audit). A letter — sometimes titled “Business Activity Questionnaire” or “Nexus Determination Questionnaire” — asks about inventory locations, employees, sales volume, and marketplaces used. This is the diversion point. Handle it right and it dies here. Handle it wrong and it becomes a formal audit.
- Notice of audit / engagement letter. Formal opening. An auditor is assigned. The exact position here depends on your own facts, so it is worth confirming with the state directly or talking to us about your situation.
- Fieldwork. The auditor pulls sample transactions, reviews exemption certificates, reconciles gross sales to filed returns, and tests taxability of your product mix.
- Assessment. A Notice of Determination (California), Notice of Deficiency, or equivalent lands with a hard protest deadline.
Typical timeline: 12–24 months
Complex multi-state cases with foreign sellers can run 30+ months. During that time, the initial exposure estimate frequently grows — sometimes 3–5x — as the auditor pulls additional data, expands the sample, and identifies untested exemption categories.
A critical point on the audit clock: the statute of limitations is not your friend if you never registered. In California, CDTFA’s standard sales tax statute of limitations is 3 years from the later of return filing date or due date, extended to 8 years if no return was filed under R&TC §6487. Most other states follow a similar pattern — a bounded lookback for registered sellers, and an effectively unlimited lookback for unregistered ones. This is why the “wait and see” strategy is catastrophic.
The 7 Audit Triggers Ecommerce Sellers Trip Most Often
Every ecommerce audit we’ve defended started with one or more of these triggers. Understanding them lets you assess your own audit risk before the state does.
1. Marketplace 1099-K vs filed returns mismatch
The single most common trigger. Even if the gap has a legitimate explanation (marketplace facilitator collected on your behalf), you now need to prove it.
2. Crossing economic nexus thresholds without registering
Wayfair opened the door in 2018 and the states walked through it: each state that levies a general sales tax now sets its own economic-nexus threshold by statute, and the thresholds are not identical to one another. Cross it and you owe registration. Here are the thresholds for the six states that audit ecommerce sellers most aggressively:
| State | Sales threshold | Transaction threshold | MF law effective |
|---|---|---|---|
| California | None | California’s marketplace facilitator rules took effect in recent years, but the exact operative date and how it applies to your sales channel depends on the fact pattern. If you sell into California through a marketplace, contact us for a current review. | |
| Texas | $500,000 | None | October 1, 2019 |
| New York | $500,000 AND 100 transactions | Both required | June 1, 2019 |
| Washington | $100,000 | None | October 1, 2018 |
| Illinois | Illinois requires a remote retailer or marketplace facilitator to collect once it reaches $100,000 or more in cumulative gross receipts from Illinois sales of tangible personal property. The separate 200-transaction test was removed with effect from January 1, 2026 and no longer applies (see IL DOR Bulletin FY 2026-12). | Disjunctive | Illinois marketplace facilitator collection obligations have been in effect for several years, though the specific effective date that governs your exposure period depends on the facts. If you have historical Illinois marketplace sales to assess, contact us for a current review. |
| Florida | None | July 1, 2021 |
3. Inconsistent nexus footprints across states
If you’re registered in eight states but shipped comparable volume into three others and never registered there, that inconsistency is itself a red flag. State DORs share data — more on this below.
4. Missing or invalid resale certificates
B2B sales without documented exemption certificates default to taxable. An auditor pulls your top 20 largest orders, sees no certificates on file, and assesses full tax. We’ve seen 7-figure assessments driven almost entirely by missing resale certs on B2B sales the seller correctly treated as exempt.
5. Marketplace facilitator confusion (double-taxed or under-taxed)
Sellers who run both Shopify direct and Amazon FBA frequently misapply MF collection rules. Common failures: not filing zero-tax returns on facilitated sales, reporting facilitated sales as “exempt” incorrectly, or (worse) collecting tax on marketplace sales the platform already collected on.
6. Prior VDA in one state flagging you to neighbors
State DORs increasingly share nexus intel. If you completed a Voluntary Disclosure Agreement in one state disclosing FBA warehouses in adjacent states, expect the adjacent states to eventually knock. This is why VDA sequencing matters — see our VDA guide for how to do this correctly.
7. Employee, inventory, or 3PL presence discovered via advertising
Your own website is evidence. A “Ships from our Nashville warehouse” tagline is admissible proof of Tennessee physical nexus. LinkedIn profiles listing employees in a state are evidence. Podcast ads mentioning your “California team” are evidence. Auditors read all of it.
Notably, in Illinois there is a specific carve-out that helps some FBA-only sellers: per Illinois Department of Revenue FAQ guidance for marketplace facilitators and sellers, inventory used strictly to fulfill orders made over the marketplace does not create physical presence nexus for the marketplace seller. This is unusual — most states treat FBA inventory as unambiguous physical nexus. But even in Illinois, adding Shopify direct sales flips the analysis immediately.
Nexus Questionnaire: The Pre-Audit Stage You Must Not Ignore
How you respond to this letter determines whether you spend the next 18 months defending a full audit or resolve the matter quietly.
What a nexus questionnaire looks like
A one-to-three page letter, usually with a form attached, asking:
- Do you have employees, contractors, or agents in this state?
- Do you store inventory here (including third-party fulfillment)?
- Do you attend trade shows or make in-person sales calls?
- What was your gross sales volume into this state by year for the past 4 years?
- Do you sell through marketplaces? Which ones?
- Are you registered for sales tax in this state? If not, why not?
The 30-day trap
Sellers see a questionnaire, aren’t sure how to answer, and put it in the “deal with it later” pile. Two things then happen:
- The deadline passes and the DOR escalates automatically to a formal audit engagement — with a much larger presumed exposure since you now look non-cooperative.
- Your right to a Voluntary Disclosure Agreement in that state usually terminates the moment the DOR makes formal contact about the specific tax at issue.
Why answering honestly (but strategically) matters
Your answers to a nexus questionnaire are sworn statements. Lie on it and you’ve now added potential fraud exposure — which in most states removes the statute of limitations entirely and can trigger criminal referral in extreme cases.
The correct posture: answer truthfully, answer narrowly (do not volunteer information not asked), and get professional representation before signing. A well-drafted questionnaire response can legitimately close the file if the facts support it — e.g., you have no inventory in the state, no employees, and your sales are all facilitated by a registered marketplace facilitator.
When to pivot to a VDA instead of responding
If the questionnaire arrives and you genuinely have unregistered nexus, the strategic move is often to not respond directly to the questionnaire and instead to open a VDA. VDA eligibility rules turn on whether the state has made contact about “the specific tax type.” A vague nexus questionnaire may not close the VDA door — but a follow-up letter naming sales tax specifically usually does.
This is a fact-pattern call. State-by-state VDA rules differ, and the eligibility window is narrow. If you’ve received a questionnaire and think you may have unregistered nexus, contact us before responding — the sequencing decision drives the entire outcome.
Sampling Methodology: Where 90% of the Assessment Is Decided
This is the single most important section of this article and the least-understood aspect of sales tax audit defense. The auditor rarely reviews every transaction in your audit period. A single anomalous month can inflate an assessment 10–20x if you accept the sample without negotiation.
Block sampling vs statistical sampling vs 100% review
Three sampling methodologies dominate:
- Block sampling.
- Statistical sampling. Auditor uses a randomized transaction sample drawn from the entire audit period.
- 100% review / detail audit. Auditor reviews every transaction. Rare for ecommerce (data volume prohibits it) but available in principle.
Each method has trade-offs. Block sampling is fast but easily distorted by seasonality (a big holiday month projected across the year). Statistical sampling is more defensible but requires the auditor to define stratification correctly — and stratification is where the fight is.
How to negotiate the sample period
You have the right to propose alternative sample periods and methodology in every major audit state. California’s CDTFA Audit Manual establishes procedures for sampling methodology including taxpayer input on sample period and stratification. Texas, New York, and Washington all publish audit manuals with equivalent provisions.
Practical levers:
- Object to sample months that contain known anomalies (a product recall, a promotional event, a one-off B2B customer surge).
- Propose a longer sample window (6–12 months) to smooth seasonality.
- Request stratified sampling by transaction size or customer type.
- Insist that facilitated marketplace sales be excluded from the taxable population entirely (the marketplace facilitator is the retailer of record).
Stratification and how it can double or halve your bill
Stratification splits the transaction population into buckets — small orders, mid orders, large orders, B2B, B2C — and samples separately from each. Done well, it isolates high-error segments (e.g., missing resale certs on B2B) from low-error ones. Done poorly (or done to the state’s advantage), it lumps everything together and lets high-value B2B errors get projected across all your B2C volume.
Projecting sample errors across the full audit period
The projection formula matters, and the arithmetic is worth working through. Take a seller with $8 million of annual sales and a four-year audit period. If the auditor’s three-month sample shows that 3% of sales were treated as exempt when they should not have been, that projects to $240,000 of under-taxed sales a year and $960,000 across the four years, and the assessment is built on that base before penalties and interest. Argue the error rate down to 1% through stratification and a better-designed sample, and the same arithmetic gives $320,000. Same audit. Same books. These are illustrative figures, not a prediction for your own file.
This is why software vendors cannot replace an audit defense practitioner. A software tool cannot argue with a human auditor about statistical sampling methodology.
Resale Certificate Defense: Reconstructing B2B Exemptions Mid-Audit
If you sell B2B on any ecommerce platform and don’t have a systematic resale certificate collection workflow, you have material undiscovered exposure right now. The good news: in most states, you can collect certificates during the audit and have them accepted if handled correctly.
Why ecommerce sellers lose the most here
Traditional distributors have well-established exemption certificate binders. Ecommerce sellers, especially those selling through Amazon Business, Shopify B2B, or Faire, often have almost nothing on file. The exemption logic lives in the platform — but the certificate itself frequently does not.
An auditor pulls your top B2B customers, asks for their resale certificates, and finds nothing. Default outcome: full tax assessed on every “exempt” sale.
The “good faith” standard state-by-state
Most states require the seller to accept exemption certificates “in good faith.” What counts as good faith varies:
- Some states require the certificate be on file at the time of sale.
- Others allow certificate collection within 60–120 days after the auditor’s request (“cure period”).
- A few allow certificate collection at any point before the assessment becomes final.
Verify the specific state’s rule at the start of every audit — the cure-period math drives the resale-cert reconstruction strategy.
Post-audit certificate collection: is it allowed?
Yes, in most cases — but time-limited. The typical workflow:
- Identify every B2B transaction in the audit sample missing a certificate.
- Extract customer contact data from your ecommerce platform.
- Draft an outreach email requesting a completed resale/exemption certificate for the specific period.
- Follow up. Twice. Three times if necessary.
- Submit collected certificates to the auditor within the cure window.
Not sure how this applies to your business? We handle US sales tax registration, filing and remittance for ecommerce sellers as a fully managed service, for one fee. Book a free consultation and we will review your own position with you.
MTC Uniform Sales & Use Tax Certificate acceptance
The Multistate Tax Commission’s Uniform Sales & Use Tax Exemption Certificate is accepted by most (but not all) states. Some states — California is the classic exception — prefer or require their own form. Verify state-by-state before sending certificates to customers; a customer who fills out the wrong form has done you no favors.
Managed Audit Programs: How to Cut Penalties to Zero
In two of the largest ecommerce audit states — California and Texas — a Managed Audit Program (MAP) exists specifically to reduce or eliminate penalties for cooperative taxpayers. Very few sellers know these programs exist. Even fewer use them correctly.
California Managed Audit Program
CDTFA offers a Managed Audit Program under California Revenue and Taxation Code provisions that allows qualifying taxpayers to self-audit under CDTFA supervision with reduced penalties. The seller performs the audit work themselves (or via a representative) under CDTFA supervision. In exchange:
- Penalties are typically waived in full.
- Interest may be reduced.
- The engagement is faster and less intrusive than a traditional audit.
Texas Managed Audit
Texas offers an analogous program. Similar structure: self-audit under Comptroller supervision with penalty relief and typically a partial interest reduction. Details on eligibility and current terms should be verified with the Texas Comptroller directly at the time of engagement — the program terms can shift.
Eligibility requirements
MAP programs generally require:
- A cooperative posture (you can’t be in active dispute with the DOR).
- Clean, complete books adequate for self-audit.
- Reasonable expectation of a material assessment (small exposures aren’t worth the state’s supervision time).
- No prior fraud history.
Trade-offs: extended SOL vs waived penalties
The catch: MAP engagements typically require the taxpayer to waive the statute of limitations for the audit period. You’re trading a bounded audit window for penalty relief. For most ecommerce sellers with a genuine deficiency, this trade favors the seller — the penalty savings exceed the SOL risk. But it is a case-by-case decision.
If you’ve received an audit notice and think MAP conversion might apply, book a consultation — we evaluate MAP eligibility as part of every audit engagement.
State-by-State Audit Aggressiveness for Ecommerce (2026)
Not every state audits the same way. Here’s the practical field guide for the six most aggressive ecommerce audit states.
California CDTFA
The largest and most operationally sophisticated state DOR. CDTFA has taken the position that maintaining inventory in California — including through Amazon FBA — can create physical-presence nexus even for sellers whose sales are entirely marketplace-facilitated, though the analysis and current enforcement posture turn on the specific facts and recent guidance. If you hold FBA inventory in California, contact us for a current review.
Practical implications:
- Dedicated remote-seller and marketplace units.
- Aggressive on FBA inventory nexus — will not accept “MF handles it” as a registration exemption.
- Willing to negotiate sampling in most cases.
- Settlement Bureau available (see settlement section below).
- Managed Audit Program active and well-run.
Texas Comptroller
Comparable size and sophistication to California. Comptroller auditors are known for detailed transaction testing and tight sampling. Texas Managed Audit Program is well-utilized. Tax rates are simpler than California (no district-tax variability of the same magnitude) but taxability rules for services and digital goods are complex.
New York DTF
New York presumes economic nexus when, in the immediately preceding four sales tax quarters, a seller had more than $500,000 in gross receipts from tangible-personal-property sales delivered into the state and made more than 100 such sales. NY audits often focus on resale certificate deficiencies.
Washington DOR
Washington’s B&O tax (business and occupation) complicates every audit — a Washington audit is often really two audits (sales tax and B&O). Washington’s economic nexus threshold is $100,000 of cumulative gross receipts sourced to the state, with no transaction-count test, so a seller of modest size can cross it on volume alone. Washington is an SST member state, which streamlines some procedural aspects but not the audit itself.
Illinois DOR
Illinois has the two-tax ROT/Use Tax split which makes audits procedurally complex. Illinois also has the unusual FBA carve-out mentioned earlier — sellers whose IL inventory is used solely for marketplace fulfillment may escape ROT registration. Once a seller adds Shopify direct sales, the analysis flips.
Florida DOR
Florida’s economic nexus law (SB 50) took effect July 1, 2021, later than most states, with a $100,000 threshold and no transaction count. Because Florida came late to economic nexus, lookback exposures for Florida are naturally shorter than for other states. Florida’s Self-Disclosure Program is a viable VDA alternative for previously-unregistered sellers.
Foreign and Non-US Ecommerce Sellers: Special Audit Considerations
If you’re a Canadian, UK, Australian, NZ, or South African ecommerce seller with US customers, you have some counterintuitive protection — and some very real exposure. Here’s what actually matters.
US sales tax is not covered by any tax treaty
The Canada-US Tax Treaty, the UK-US Tax Treaty, and every other US bilateral tax treaty covers income tax — not state sales tax. Sales tax is a state-level transaction tax, and no treaty preempts state authority to collect it from sellers who have nexus. Foreign sellers get zero treaty protection on US sales tax obligations.
How states pursue foreign sellers without US bank accounts
The practical enforcement toolkit against non-US sellers:
- Marketplace payout suspension. States can and do contact Amazon, Shopify, eBay, and other marketplaces to withhold seller payouts pending compliance. Amazon in particular is highly responsive to state DOR outreach.
- Bank levy on any US-domiciled account. Even a Payoneer or Wise USD account with a US routing number can be levied.
- Referral to Customs. Extremely rare, but states can (in theory) refer to CBP for inspection holds on inbound inventory shipments.
- Judgment collection. States can obtain judgments in US courts and — depending on the seller’s home country — pursue reciprocal enforcement.
Power of attorney and US-based representation
You do not need to appear in person. You do not need a US address. You do not need to travel. A licensed US-based representative filing a state Power of Attorney form (CDTFA-392 in California, Form 85-113 in Texas, POA-1 in New York, and equivalents in every state) can handle the entire audit under your authority.
This is exactly the scenario our practice was built for. If you’re a non-US seller staring at a state audit notice, contact us — we handle audits for foreign sellers with no US presence as a core service.
The Assessment, Appeals, and Settlement Process
Once the audit closes, a Notice of Determination lands with a strict protest deadline. Miss it and the assessment becomes final — with no meaningful path to reduce it.
Notice of Determination / Deficiency
The formal assessment document. It lists the tax deficiency, penalties, and interest. It states the protest deadline in bold. Read the deadline first. Everything else can wait.
Protest / petition for redetermination deadlines
Deadlines vary by state:
- California: Petition for Redetermination must be filed within 30 days of the Notice of Determination.
- Texas: 60 days for petition for redetermination.
- New York: 90 days for petition to the Division of Tax Appeals.
- Washington: 30 days for petition for review.
Miss the deadline and — barring extraordinary circumstances — the assessment becomes final and collectible. This is the single most common way ecommerce sellers turn a manageable audit into a business-ending event.
Administrative hearing
Post-protest, most states offer an administrative hearing before an independent Office of Tax Appeals (California), Administrative Law Judge (New York, Washington), or equivalent. This is where properly-argued sampling defenses, resale certificate reconstructions, and taxability positions get their real hearing.
Settlement bureaus and how to use them
Several states operate dedicated settlement bureaus that can resolve audits at material discount without full litigation. California’s CDTFA Settlement Bureau, New York’s BCMS (Bureau of Conciliation and Mediation Services), and Texas’s Independent Audit Review are the most prominent.
Realistic settlement outcomes with proper representation: 30–70% reductions from the initial assessment are common. Cases with genuine legal weakness on the state’s side (unclear taxability, procedural defects in the audit, sampling errors) settle at the higher end of that range.
When to pay under protest and litigate
Rare, but sometimes appropriate. If the assessment involves a bright legal issue with statewide implications — a taxability question, an unconstitutional statute, a sampling methodology used across many audits — paying under protest and taking the case to state court can be the right move. This is a case-by-case decision that requires litigation counsel.
DIY vs Hiring an Audit Defense Firm: Honest Cost/Outcome Comparison
What you’ll spend in time and internal resources doing it yourself
A typical ecommerce audit consumes 40–200+ hours of taxpayer time over 12–24 months. That’s your founder’s time, your controller’s time, or your bookkeeper’s time — pulled from running the business. And that’s before accounting for the very high probability of expensive mistakes: missed protest deadlines, badly-drafted questionnaire responses, blown VDA windows, unfavorable sampling agreements signed without negotiation.
Typical firm fees vs typical assessment reduction
Boutique tax firms and CPA practices typically charge $300–$600/hour for audit representation. A moderate ecommerce audit runs 40–80 professional hours; a complex multi-state case can run 200+. That’s a $15K–$100K+ hourly bill, unbudgeted, mid-audit.
Contrast that with typical assessment reduction: 30–70% off the initial exposure. On a $500K initial assessment, that’s $150K–$350K in savings. The math on professional representation is usually not close.
Why software companies can’t represent you
This is the point most ecommerce sellers get wrong. The major sales-tax software platforms are calculation and filing tools. They do not have licensed practitioners on staff who can file a Power of Attorney and speak to an auditor on your behalf. When you get an audit notice, they will politely refer you elsewhere. You have paid for a product; you have not paid for a defender.
Boutique CPA firms and specialty sales-tax practices — including ours — are structured differently. We are licensed practitioners who represent clients before state DORs under formal POA. The auditor’s calls, emails, records requests, and settlement offers all route through us.
What our done-for-you audit defense includes
A single flat engagement fee covers:
- Power of attorney filed within 48 hours of engagement.
- Every auditor interaction handled by us — you never speak to the auditor.
- Records request response, sampling negotiation, resale certificate reconstruction, taxability defense, Managed Audit Program conversion where beneficial, protest drafting, and settlement negotiation.
- Post-audit remediation: registration cleanup in adjacent states, VDA sequencing, and ongoing filing service if needed.
How Sales Tax Compliance USA Handles Your Audit — Start to Finish
Here’s exactly what happens when you engage us on an audit — whether you’re a domestic Shopify seller in Denver or an Australian FBA seller in Sydney.
Step 1: Power of attorney filed within 48 hours
The moment you sign the engagement letter, we file the state POA form. From that point forward, every auditor communication legally routes to us. You are out of the direct line of fire.
Step 2: Auditor communication routed through us
We take the auditor’s initial records request, schedule the opening conference, and set the tone. First calls with auditors matter — they establish the cooperative-but-firm posture that defines the rest of the audit.
Step 3: Data room + sampling defense
We pull your ecommerce data (Amazon Seller Central, Shopify, eBay, Etsy, Walmart, direct-website reports), reconcile to filed returns, and identify every material sampling risk. We then negotiate sample period, stratification, and methodology with the auditor before the sample gets pulled — not after.
Step 4: Resale certificate reconstruction
We identify every B2B transaction in the audit population without a certificate on file, run the customer outreach workflow, and get certificates submitted within the state’s cure window.
Step 5: Protest, settlement, or MAP conversion
Depending on the audit trajectory, we route to Managed Audit Program conversion (best-case), settlement negotiation with the state’s settlement bureau (common), or protest and administrative hearing (where warranted). We recommend the path with the best expected outcome for your specific fact pattern.
Step 6: Post-audit remediation and multi-state VDA cleanup
After the audit closes, we sequence VDAs in any adjacent states where the audit uncovered unregistered exposure — before the audited state tips off its neighbors. We also handle prospective registration and ongoing filing in every state where you now have obligations.
One flat fee. One point of contact. You never speak to the auditor.
Paul le Roux, CA(SA), tax practitioner, leads audit defense for Sales Tax Compliance USA. Our practice specializes in ecommerce sellers, cross-border founders, and non-US entities with US state audit exposure. This is not a side offering — it is what we do.
Don’t want to figure this out yourself? Sales Tax Compliance USA handles your entire US sales tax audit — power of attorney through settlement — for a single fee. Book a free consultation or learn more about our service.
Frequently Asked Questions
How long does an ecommerce sales tax audit take?
Most ecommerce audits run 12–24 months from opening letter to final assessment. Complex multi-state cases and audits involving foreign sellers can run 30+ months. The initial exposure estimate frequently grows during the audit as auditors pull additional data.
Can a software company represent me in an audit?
No. Sales-tax software companies are calculation and filing tools. They are not licensed to file a Power of Attorney and represent you before a state DOR. When you receive an audit notice, they will refer you to outside counsel. Only licensed tax practitioners (CPAs, EAs, and equivalent) can formally represent you in an audit.
What triggers a sales tax audit for an Amazon or Shopify seller?
The seven most common triggers: marketplace 1099-K vs filed returns mismatch; crossing economic nexus thresholds without registering; inconsistent nexus footprints across states; missing resale certificates on B2B sales; marketplace facilitator confusion; prior VDA in one state alerting neighboring states; and physical evidence of nexus (employees, inventory, 3PL, advertising).
How far back can a state audit me if I never registered?
For unregistered sellers, most states can effectively look back without limit — the statute of limitations only starts running once returns are filed. In California, the 3-year statute of limitations extends to 8 years when no return was filed, per R&TC §6487. Other major audit states follow similar patterns. This is why “wait and see” is catastrophic for unregistered sellers.
Can I still get a Voluntary Disclosure Agreement after receiving a nexus questionnaire?
Possibly. VDA eligibility typically terminates once a state has made contact “about the specific tax type.” A vague nexus questionnaire may not close the VDA door if it doesn’t specifically identify sales tax. A follow-up letter naming sales tax specifically usually does. If you’ve received a questionnaire, contact us before responding — the sequencing decision drives the entire outcome.
What is a Managed Audit Program and am I eligible?
A Managed Audit Program (MAP) allows a taxpayer to self-audit under DOR supervision in exchange for penalty relief and often reduced interest. California and Texas both operate active MAP programs. Eligibility generally requires cooperative posture, clean books, and a material expected assessment. The trade-off: MAP typically requires waiving the statute of limitations for the audit period.
I’m a non-US seller with no US bank account — can a state actually collect from me?
Yes. States can (and do) contact marketplaces to withhold seller payouts, levy any US-domiciled bank account (including USD accounts held by Payoneer, Wise, or similar), and obtain US court judgments. The Canada-US, UK-US, and other bilateral tax treaties do not protect against state sales tax — those treaties cover income tax only. Foreign sellers get zero treaty protection.
How much does professional sales tax audit defense cost?
Hourly firms typically charge $300–$600/hour for audit representation, and audits run 40–200+ professional hours. Total costs range from $15K to well over $100K on an hourly model. Our done-for-you audit defense is priced as a single flat engagement fee, scoped to the audit’s complexity — no billable-hour surprises mid-engagement.
Can I collect resale certificates from my customers after the audit has started?
In most states, yes — within the auditor’s cure period (typically 60–120 days from request). A systematic reconstruction workflow can recover 60–80% of at-risk B2B exemption revenue. The specific rules vary by state; verify the cure window at the start of the audit.
Should I respond to a state nexus questionnaire on my own?
Almost always no. Your answers become sworn statements used against you in fieldwork. Questionnaires deserve professional review before signing — the response drives whether the file closes or escalates to a formal audit.
What happens if I ignore a sales tax audit notice?
The DOR will proceed without your input. They will issue an assessment based on estimated data (usually 1099-K totals treated as fully taxable), and that assessment will become final once the protest deadline passes. Ignoring an audit notice is the fastest path to the worst possible outcome.
Can the auditor’s assessment be reduced through settlement?
Yes. With proper representation, 30–70% reductions from initial assessment are common through state settlement bureaus (California CDTFA Settlement Bureau, New York BCMS, Texas Independent Audit Review, and equivalents). Cases with genuine legal weakness on the state’s side settle at the higher end of that range.
Last verified: July 2, 2026.
This article is for informational purposes only and does not constitute tax advice. Consult a licensed tax professional before acting on any of this content.
