Sales Tax Nexus Study: Complete Guide for Businesses in 2026

In the complex landscape of post-Wayfair sales tax compliance, a sales tax nexus study has become an essential tool for businesses operating across multiple states. Whether you are a growing e-commerce retailer, a SaaS provider, or a traditional brick-and-mortar business expanding online, understanding where you have sales tax nexus and consequently, where you must collect and remit sales tax is critical to avoiding costly penalties and legal complications.

This comprehensive guide will explain what a nexus study entails, why your business likely needs one, and how to conduct a thorough analysis that will keep your company compliant with ever-changing state tax laws. For a deeper dive into the fundamentals, refer to our complete nexus study guide.

What Is a Sales Tax Nexus Study?

A sales tax nexus study is a comprehensive analysis that determines where a business has established sufficient connection or nexus with a state to trigger sales tax collection obligations. Since the landmark South Dakota v. Wayfair Supreme Court decision in 2018, nexus can be established through economic activity alone, without any physical presence in a state.

Key aspects of a nexus study include:

• Reviewing all sales transactions by destination state
• Analyzing physical presence factors (offices, warehouses, employees)
• Examining economic nexus thresholds for each state
• Identifying marketplace facilitator obligations
• Assessing affiliate and click-through nexus risks

Each state sets its own economic nexus thresholds, typically based on annual revenue or transaction volume into that state. Understanding these varying requirements is essential for multi-state businesses.

Why Your Business Needs a Nexus Study

The consequences of failing to identify and comply with nexus obligations can be severe. Here are the primary reasons every multi-state business should conduct a nexus study:

Avoiding Costly Penalties and Interest

States can assess back taxes, penalties, and interest for failure to collect sales tax when nexus exists. These assessments can date back several years and reach hundreds of thousands or even millions of dollars for larger businesses. A proactive nexus study helps identify obligations before states initiate contact through an audit.

Facilitating Business Growth and Expansion

As your business grows into new states or sales channels, your nexus profile changes. A nexus study provides the foundation for understanding where expansion creates new tax obligations, enabling better strategic planning and compliance management.

Preparing for State Audits

If your business is selected for a sales tax audit, having conducted a documented nexus study demonstrates good faith compliance efforts. It also ensures you are prepared with the documentation needed to defend your filing positions. Learn more about audit preparation in our ecommerce compliance guide.

Voluntary Disclosure Opportunities

If a nexus study reveals prior period non-compliance, voluntary disclosure agreements (VDAs) may be available. These programs often limit lookback periods and reduce penalties for businesses that proactively come forward.

When to Conduct a Nexus Study

While businesses should regularly assess their nexus positions, certain events trigger an immediate need for a comprehensive study:

• Post-Wayfair uncertainty: If you have not assessed economic nexus since the 2018 Wayfair decision
• Revenue threshold approach: When sales to a specific state approach economic nexus thresholds
• Business model changes: New sales channels, marketplace participation, or geographic expansion
• Remote work policies: Employees working from home in new states can create physical nexus
• Inventory changes: Using third-party fulfillment centers or drop-shipping arrangements
• M&A activity: Acquiring another business that may have created nexus in new states

Key Components of a Nexus Study

Transaction Analysis

The foundation of any nexus study is a detailed analysis of sales transactions by destination state. This includes:

• Total revenue by state for the past 12-36 months
• Number of transactions by state
• Sales of taxable vs. exempt products or services
• Marketplace-facilitated vs. direct sales

Physical Presence Review

Despite the focus on economic nexus after Wayfair, physical presence remains a primary nexus creator. Your study should examine:

• Office locations and facilities
• Warehouse and inventory storage locations
• Employee locations (including remote workers)
• Property and equipment ownership in each state

Affiliate and Related Party Analysis

Many states have affiliate nexus laws that attribute nexus to a business based on relationships with related entities. Review any affiliates, subsidiaries, or related parties that might create nexus on your behalf.

How to Conduct a Nexus Study

While larger businesses often engage tax professionals for nexus studies, smaller companies can conduct effective studies internally by following this structured approach:

Step 1: Gather Transaction Data

Compile 12-36 months of sales data, organized by destination state. Include both dollar amounts and transaction counts. Most accounting systems can generate this through sales reports filtered by shipping or billing state.

Step 2: Obtain Current Threshold Information

For each state where you have sales, identify the current economic nexus threshold. These thresholds vary widely from $100,000 in annual sales to 200 transactions, or combinations of both criteria.

Step 3: Compare Activity to Thresholds

Line up your transaction data against each state threshold to identify where nexus likely exists. Document both current positions and states where you are approaching thresholds.

Step 4: Physical Presence Assessment

Map physical presence factors across all states. Include indirect presence through affiliates, third-party fulfillment services, and remote employees.

Step 5: Document and Monitor

Create a nexus matrix showing your position in each state. Implement ongoing monitoring for states where activity approaches thresholds.

Risks of Not Conducting a Nexus Study

Businesses that fail to assess their nexus positions face significant risks:

• Unassessed tax liability: Unknown back-tax obligations that may be discovered during audits
• Penalty and interest accrual: Continued non-compliance means growing penalties
• Customer exposure: States may pursue customers for use tax if you failed to collect sales tax
• Reputational damage: Public record of tax compliance issues can harm business relationships
• Transaction complications: Tax issues discovered during due diligence can derail M&A deals

Conclusion: Making Nexus Studies Part of Your Tax Strategy

The post-Wayfair landscape requires businesses to take a proactive approach to sales tax compliance. A sales tax nexus study is the foundational step in understanding your obligations and ensuring compliance across all states where you do business.

Given the complexity of varying state thresholds and the multiple ways nexus can be established economic activity, physical presence, affiliate relationships, and marketplace participation regular nexus studies should be a core component of your tax compliance strategy. Businesses that conduct thorough nexus studies and act on their findings can operate with confidence, knowing they are meeting their obligations while minimizing exposure to penalties and interest.

If your business sells across state lines and has not conducted a nexus study since the Wayfair decision or if significant changes have occurred in your business model, sales volume, or physical presence now is the time to assess your nexus position. The investment in a comprehensive study is minimal compared to the potential costs of non-compliance discovered through a state audit.