Understanding Sales Tax Nexus in 2026

Sales tax nexus is the connection that can allow a state to require a business to collect and remit sales tax. In 2026, that connection does not depend solely on having an office, store, or employee in the state. An out-of-state seller may have a collection obligation based on its business activity and substantial virtual connections with customers in a state.

There is no federal sales tax registration that covers the entire United States. The IRS directs businesses with sales-tax collection questions to the appropriate state revenue department and state government websites. As a result, a business must evaluate its activity separately in each state where it makes sales and must also consider whether any relevant local jurisdiction administers its own tax.

What Sales Tax Nexus Means in 2026

Nexus is not the tax rate, and it is not the registration itself. It is the legal connection that may give a taxing jurisdiction authority over a seller. Once a business determines that its activities create nexus under a state’s current rules, it can investigate registration, collection, return, and remittance requirements with that state’s revenue agency.

The modern framework is heavily influenced by South Dakota v. Wayfair. In that case, the U.S. Supreme Court overruled the rule that physical presence was required before a state could impose sales-and-use-tax collection duties on an out-of-state seller. The absence of property or personnel in a state therefore does not, by itself, establish that a seller has no obligation there.

The constitutional analysis discussed after Wayfair recognizes substantial nexus where sellers avail themselves of the substantial privilege of conducting business in a state, including through substantial virtual connections. That standard does not create one statutory threshold for every state. Each state’s law must still be reviewed independently.

It is especially important not to treat the figures in the Wayfair case as a universal test. The South Dakota law examined by the Supreme Court applied to sellers that annually delivered more than $100,000 of goods or services into South Dakota or made 200 or more delivery transactions there. Those figures described the South Dakota law before the Court; they are not a nationwide threshold and do not automatically control another jurisdiction’s requirements.

Key Requirements to Evaluate

Physical and economic connections

A nexus review should begin with the ways the business connects with each state. Do not stop the review merely because all sales occur remotely. The constitutional framework permits a state to impose collection duties without physical presence, while substantial virtual connections can support substantial nexus.

At the same time, nexus is not based on a single federal test. Review the business’s actual operations and sales data against the current law and guidance published by each potentially relevant state. If the business operates in several jurisdictions, a repeatable tracking method is useful. See How to Track Sales Tax Nexus Across Multiple States in 2026 for a multi-state organizational approach.

Constitutional limits

State taxing authority remains subject to federal constitutional limits. Under the Commerce Clause framework, a state tax must apply to an activity with substantial nexus, be fairly apportioned, avoid discrimination against interstate commerce, and be fairly related to services provided by the state.

Due process is a separate consideration. It requires minimum contacts that give an out-of-state seller fair warning that it may be subject to the taxing state’s authority. These constitutional standards help define the limits of state power, but they do not replace the need to analyze the applicable state statutes and administrative rules.

Online transactions

Online sales are not categorically exempt from sales tax. The Internet Tax Freedom Act restricts taxes on internet access and multiple or discriminatory taxes on electronic commerce, but it does not generally prevent an otherwise valid, nondiscriminatory sales tax from applying to online transactions. Under that federal law, comparable electronic and nonelectronic transactions generally must face the same tax obligations and rates.

Accordingly, describing a business as “online only” does not resolve nexus. The business must still identify the states connected to its sales and evaluate those states’ current rules.

Step-by-Step Nexus and Registration Process

1. Map where the business conducts activity. Create a state-by-state list based on the company’s operations and sales. Keep the review broad enough to capture both physical and remote commercial connections instead of limiting it to states containing a business location.
2. Organize state-level sales records. Use consistent records that let the business evaluate its activity for each jurisdiction. Preserve the period, transaction count, sales amount, and relevant transaction details needed to compare operations with current state guidance. Avoid assuming that a threshold taken from another state applies.
3. Check each state revenue agency. Determine whether the business’s activities create a registration and collection obligation under the state’s current law. Because sales-tax registration is a state matter rather than a federal process, use the relevant state revenue department and state government resources for the controlling requirements.
4. Review local administration. Do not assume that state registration necessarily completes every local step. GAO found that some local jurisdictions administer sales taxes separately, which can potentially require separate registrations, returns, remittances, and audits. Whether this applies depends on the particular state and locality, so confirm the current local structure rather than relying on a generalized list.
5. Complete the applicable registration process. Follow the instructions of each jurisdiction in which registration is required. The responsible agency, application details, and related procedures should be confirmed directly for that jurisdiction. Businesses focused on particular states can consult the related guides to the California CDTFA sales tax registration process and Colorado sales tax registration as starting points for state-specific planning.
6. Document the conclusion and monitoring plan. Record which states were reviewed, what business data was used, which agency guidance was consulted, and what action was taken. Schedule periodic reviews and additional checks when business activity changes. A documented process helps prevent a one-time analysis from becoming an outdated assumption.

Practical Mistakes to Avoid

• Using physical presence as the only test. Wayfair eliminated physical presence as a mandatory constitutional prerequisite for an out-of-state seller’s collection duty. A remote seller should not end its analysis merely because it lacks an in-state facility or workforce.
• Applying South Dakota’s case figures nationwide. The sales and transaction figures associated with Wayfair came from the South Dakota statute considered in that case. They are not a federal safe harbor or a uniform registration threshold.
• Treating internet sales as tax-free by definition. Federal protections for internet access and against discriminatory electronic-commerce taxes do not create a general sales-tax exemption for online purchases.
• Looking for an IRS sales tax permit. State sales-tax collection questions belong with state revenue departments and relevant state government websites. An EIN or another federal filing does not substitute for a state sales-tax registration.
• Overlooking separately administered local jurisdictions. In some places, local administration may add registration, return, remittance, or audit obligations beyond the state-level process. Verify the current arrangement for every location that may be relevant.
• Combining sales tax and federal excise tax analysis. The IRS notes that certain businesses may collect federal excise taxes reported on Form 720. Those federal excise-tax obligations are distinct from state sales-tax registration and should be handled as a separate compliance question.
• Relying on an old nexus review. A prior conclusion may no longer fit after the business enters new markets, changes how it operates, or records different sales activity. Reconcile the analysis to current state guidance and current business data.

Next Steps for a Defensible 2026 Review

Start with a complete state-by-state picture rather than registering everywhere automatically or assuming no registration is needed. Prioritize jurisdictions where the business has meaningful operations, customer activity, or other connections. Then compare the facts with current guidance from the responsible state revenue agency and check for independently administered local taxes.

For each jurisdiction, retain a short nexus file containing the date of review, the data examined, the conclusion, and any resulting registration action. Assign responsibility for monitoring changes and for escalating uncertain situations to a qualified state and local tax professional. This creates a practical compliance record while recognizing that constitutional nexus principles and state-specific registration rules answer different parts of the question.