Unpaid Sales Tax Consequences and Resolution

Sales tax enforcement has intensified significantly since 2018. States are short on revenue, data-sharing between states and the IRS has improved, and the South Dakota v. Wayfair ruling eliminated the physical presence requirement for sales tax nexus.

If your business has unpaid sales tax, you are facing a state revenue department that has more tools and more motivation to collect than at any prior point in history.

This guide covers what happens when you have unpaid sales tax, how penalties compound, and what resolution options exist.

What Triggers a Sales Tax Problem

Not Registering in Required States

Before you can collect and remit sales tax, you must register with each state's revenue department. Many businesses, especially online sellers, skip this step because they do not realize the obligation exists.

After Wayfair, economic nexus thresholds apply in virtually every state with a sales tax. The most common threshold: $100,000 in sales or 200 transactions in a state within a calendar year.

If you hit these thresholds in a state and never registered, you have created a retroactive sales tax liability dating back to when you first exceeded the threshold.

Collecting Tax but Not Remitting It

Some businesses collect sales tax from customers (it shows up on every receipt) but fail to remit it to the state on schedule. This is treated harshly because you took money from customers specifically for the state and kept it.

States can classify this as fraud in egregious cases, triggering civil and criminal penalties well beyond the standard rate.

Under-Collecting or Miscategorizing Products

Tax rates and taxable categories vary by state and sometimes by county or city. Common errors include:

• Applying the wrong rate for a customer's location
• Treating taxable items as exempt
• Not charging tax on shipping and handling in states where it is taxable
• Missing destination-based rate differences

An audit that finds systematic miscategorization can result in a large retroactive assessment.

Missing Nexus from Remote Employees or Contractors

Having a remote employee, independent contractor, or even a stored inventory in a state can create physical nexus. Businesses that use fulfillment centers (including Amazon FBA) may have nexus in states where inventory is stored.

How Sales Tax Penalties Work

Each state has its own penalty structure, but common categories include:

• Late filing penalty: Typically 5-25% of the tax due, assessed per return period
• Late payment penalty: Similar rate applied to unpaid balances
• Negligence penalty: Additional 10-25% when the state determines underpayment resulted from negligence
• Fraud penalty: Up to 50-100% of unpaid tax in cases of intentional evasion
• Interest: Accrues daily from the original due date at state-specific rates (commonly 6-12% annually)

A three-year sales tax audit covering monthly returns in a state like California or Texas can produce penalty assessments equal to 40-60% of the underlying tax liability.

The Sales Tax Audit Process

Most sales tax audits begin with a letter from the state revenue department requesting records for a specific period. Common triggers:

• Information sharing from other states or the IRS
• Discrepancy between your federal income and your state sales tax filings
• Industry-specific audit sweeps
• Complaints or tips
• Random selection

The auditor will typically request:

• Sales records, invoices, and receipts
• Exemption certificates for tax-exempt sales
• Purchase records
• General ledger
• Bank statements to cross-verify deposits

If you cannot produce documentation for claimed exempt sales, the auditor will estimate the tax owed using a statistical sampling method. Statistical sampling often produces assessments larger than what was actually due, because gaps in records are resolved in the state's favor.

Voluntary Disclosure Agreements

If you have unreported sales tax exposure in states where you have not been audited or contacted, a Voluntary Disclosure Agreement (VDA) is often the best path.

Under a VDA:

• You come forward proactively before the state contacts you
• Most states limit the lookback period to three or four years (versus the standard seven-year audit window or unlimited period for fraud)
• Penalties are often reduced or waived entirely
• Interest is typically still owed
• You register, file, and pay as part of the agreement

The Multistate Tax Commission (MTC) offers a streamlined VDA program for registering in multiple states simultaneously. This is especially useful for e-commerce businesses with nexus in many states.

Once a state has audited you or sent a nexus questionnaire, the VDA option for that state is generally no longer available.

Resolving an Existing Sales Tax Assessment

Protest the Assessment

Most states give you 30-60 days to protest an audit assessment. If you believe the auditor made errors, used flawed sampling methodology, or applied the wrong rate, file a formal protest.

Include:

• Specific items in the assessment you dispute
• Documentation supporting your position
• Any exemption certificates you could not provide during the audit

Payment Plans

Every state offers some form of installment agreement for assessed sales tax. Terms vary widely. Some states require a substantial down payment. Others offer extended terms similar to the IRS 72-month plan.

Penalty Abatement

Many states will reduce or waive penalties if you can demonstrate:

• Reasonable cause (reliance on bad advice, natural disaster, serious illness)
• No prior compliance issues
• Full payment of the underlying tax

Penalty abatement requests are more likely to succeed when submitted proactively, before the state has spent collection resources on your account.

Offer in Compromise (State)

A minority of states offer an OIC-type settlement for sales tax debt, typically reserved for cases where the business is insolvent or the liability would cause severe financial hardship.

Closing the Business Does Not Eliminate the Debt

A common misconception: if the business closes, the sales tax liability disappears. It does not. Many states hold owners personally liable for sales tax collected but not remitted. Even in states that do not impose personal liability automatically, a successor liability claim can reach assets transferred during the business wind-down.

Staying Current After Resolution

Once you have resolved back sales tax, the most important step is maintaining ongoing compliance:

• Register in every state where you have nexus
• Use automated sales tax software (Avalara, TaxJar, Vertex) that calculates correct rates at point of sale
• File returns on time even for zero-liability periods (many states require zero returns)
• Update nexus analysis annually as your business grows

States communicate with each other. A resolution in one state followed by a new nexus problem in another sends a signal that compliance is not a priority.

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Dealing with unpaid sales tax in one or more states? A tax professional experienced in multi-state resolution can negotiate your penalties, navigate the VDA process, and get you current. Get connected today.