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Sales Tax for Online Merchants

Sales Tax for Online Merchants: Nexus, Registration, and Marketplace Rules Explained “What is the U.S. sales-tax rate?” For an online merchant, that question is missing most of the information needed to give a useful answer. Before determining a rate, a merchant may need to know:

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Sales Tax for Online Merchants: Nexus, Registration, and Marketplace Rules Explained

“What is the U.S. sales-tax rate?”

For an online merchant, that question is missing most of the information needed to give a useful answer.

Before determining a rate, a merchant may need to know:

Which state is involved?

Which local jurisdiction applies?

Does the seller have sales-tax nexus there?

Is the product or service taxable?

Was the transaction made directly or through a marketplace?

Only after those questions are answered does calculating the tax rate become meaningful.

That is the fundamental difference between sales tax for online merchants and the national VAT or GST systems many international sellers are more familiar with. U.S. general sales taxes are primarily imposed at the state and local level, and states and municipalities can apply different rates and rules to different products.

For ecommerce businesses, U.S. sales-tax compliance is therefore best treated as a jurisdiction-and-nexus problem, not simply a checkout-rate problem.

The practical sequence is:

Selling channel → state → nexus → taxability → marketplace responsibility → registration → calculation and collection → filing and remittance

Why U.S. sales tax is different from VAT

Sales tax and value-added tax are both forms of consumption taxation, but the compliance models are different.

A VAT system generally applies tax through multiple stages of the supply chain, with businesses commonly charging output VAT and recovering qualifying input VAT.

U.S. retail sales tax is generally imposed at the retail-consumer stage.

More importantly for international merchants, there is no single U.S. national ecommerce sales-tax rate or one national registration threshold.

State and, in many jurisdictions, local rules affect:

nexus;

registration;

product taxability;

rates;

exemptions;

sourcing;

marketplace treatment;

returns and filing frequency.

A merchant selling the same item to customers in two U.S. states can therefore face different tax treatment.

Even within one state, the destination can matter because local taxes may differ. California, for example, publishes sales and use tax rates by city and county, while Texas provides address-based rate tools and separate rules for local use tax.

That is why a global checkout should not contain one field labeled simply:

U.S. sales tax = X%

The tax determination needs more context.

What does sales-tax nexus mean?

Sales-tax nexus is the level of connection between a seller and a state that can allow the state to impose sales-tax collection responsibilities on that seller.

Nexus is not the same as registration.

Think of the sequence this way:

Nexus

Why the state has sufficient connection to impose the obligation.

↓

Registration

The administrative process through which the merchant obtains the relevant state sales-tax permit or account.

↓

Collection and filing

The operational obligations that follow where applicable.

A seller should therefore determine whether it has nexus before treating registration as merely another account-setup task.

Physical nexus still matters

Economic nexus receives much of the attention in ecommerce, but traditional physical connections remain relevant.

Depending on state law, potentially relevant factors can include:

offices;

stores;

employees or representatives;

warehouses;

inventory;

equipment;

other property or business activity in the state.

California, for example, identifies maintaining inventory or a place of business, having sales or delivery representatives, and owning or leasing tangible property in the state among activities that can create physical presence.

This matters particularly for ecommerce businesses using distributed fulfillment.

A merchant may think:

“We have no U.S. stores.”

while inventory owned by the merchant is physically stored in a fulfillment facility in one or more states.

That requires a different nexus analysis from a business shipping every U.S. order from overseas.

What is economic nexus for ecommerce?

Economic nexus allows a state to establish sales-tax collection obligations based on a seller's level of economic activity in the state even when the seller lacks traditional physical presence there.

Following the U.S. Supreme Court's 2018 South Dakota v. Wayfair decision, states can impose collection responsibilities based on economic presence rather than requiring physical presence as the universal constitutional prerequisite. Texas's Comptroller, for example, explains its remote-seller rules in direct response to that decision.

But this does not mean there is now one nationwide economic-nexus threshold.

States define their own tests.

Current examples show how different the rules can be

The following examples are illustrative, not a complete 50-state nexus table. They were verified against the relevant state authorities in August 2026.

State

Illustrative remote-seller economic-nexus test

Important measurement detail

California

More than $500,000 of qualifying tangible-personal-property sales for delivery into California

Measures the preceding or current calendar year; marketplace sales can count toward the threshold.

New York

More than $500,000 of qualifying gross receipts and more than 100 sales

Both tests must be met during the immediately preceding four sales-tax quarters.

Texas

Remote sellers under $500,000 of total Texas revenue in the preceding 12 calendar months have a safe harbor

The measurement includes taxable and nontaxable sales and can include marketplace sales.

Florida

More than $100,000 in taxable remote Florida sales

Measured over the previous calendar year.

Illinois

$100,000 or more in cumulative gross receipts from qualifying sales to Illinois purchasers

From January 1, 2026, the prior 200-transaction test no longer applies.

This table demonstrates why merchants should not maintain one internal field called:

U.S. nexus threshold

The threshold can differ in:

amount;

whether the rule uses “greater than” or “at least”;

measurement period;

type of revenue counted;

products included;

treatment of marketplace transactions;

transaction-count requirements.

Threshold logic needs to be modeled state by state.

Nexus is not the same as a tax rate

This distinction is easy to miss.

An economic-nexus threshold answers:

Does this level of activity potentially create a collection obligation?

A tax rate answers:

If this transaction is taxable and the seller is responsible for collection, how much tax applies?

The two should never be configured as the same decision.

A merchant can cross an economic-nexus threshold but still make transactions that are exempt or nontaxable.

Conversely, an item may generally be taxable in a state even though a particular remote seller has not yet established a collection obligation.

Product taxability comes before rate calculation

Knowing the customer's address still does not tell the merchant how much sales tax to charge.

The next question is:

Is this specific product or service taxable in this jurisdiction?

States classify products differently.

For example, Pennsylvania states that its sales and use tax generally applies to retail sales of tangible personal property, including digital products, while listing major exemptions including most clothing, qualifying food, textbooks, and prescription drugs.

New York has a different structure. Eligible clothing and footwear costing less than $110 per item or pair are exempt from the state's 4% sales tax, while local treatment can vary by jurisdiction. The state's guidance was updated in April 2026.

That produces an important operational distinction:

Taxability

Is the product subject to tax?

versus

Rate calculation

What state and local rate applies to this taxable transaction?

A perfect tax-rate database cannot correct an incorrect product classification.

For ecommerce businesses carrying multiple product categories, product tax codes or equivalent taxability logic can therefore be just as important as customer-address data.

Sales-tax registration comes after the nexus analysis

Once a merchant determines that it has a registration and collection obligation in a state, it generally needs to register with the relevant state tax authority before collecting tax.

The exact process varies.

Registration may result in:

a sales-tax permit;

a use-tax registration;

a vendor certificate;

another state-specific account.

Merchants should avoid collecting sales tax merely because they anticipate crossing a threshold without first determining the applicable state's registration requirements.

Registration also creates ongoing administrative obligations.

Those can include:

filing returns;

reporting taxable and exempt sales;

remitting collected tax;

maintaining exemption documentation;

keeping transaction records.

Registration is therefore not the end of the process.

It is the beginning of the filing lifecycle.

Filing requirements differ too

The filing cadence is not universal.

A state may assign monthly, quarterly, annual, or another filing frequency depending on its rules and the seller's activity.

Texas, for example, notifies taxpayers whether they will file monthly or quarterly, with annual filing available for qualifying taxpayers. Its filing guidance includes monthly, quarterly, and yearly sales-tax schedules.

New York also makes an important operational point: a business that remains registered can be required to continue filing returns for each reporting period even when sales later fall below the remote-seller threshold.

That means the merchant's sales-tax system needs to track more than tax collected.

Useful operational data include:

registered jurisdictions;

filing frequency;

filing status;

due periods;

marketplace sales;

direct sales;

taxable sales;

exempt sales;

tax collected;

tax remitted.

Marketplace sales can change who collects the tax

Marketplace facilitator laws add another layer.

In many states, qualifying marketplace operators can be treated as responsible for collecting and remitting sales tax on transactions they facilitate for third-party sellers.

That does not mean:

“If I sell on a marketplace, sales tax is no longer my problem.”

The correct analysis is transaction-specific.

Marketplace sale

A marketplace may be responsible for collecting and remitting tax on the facilitated sale under the state's marketplace rules.

Direct sale

The merchant may still be responsible for collection on sales made through its own website if the seller has nexus and the transaction is taxable.

California illustrates the distinction clearly. A qualifying marketplace facilitator is generally responsible for collecting and paying tax on facilitated sales. But a marketplace seller making direct California sales can still have its own registration and collection responsibilities. California also includes marketplace sales when determining a seller's economic nexus.

Texas follows a similarly important split: marketplace providers can collect and remit tax on facilitated transactions, while a remote seller above the state's safe harbor remains responsible for qualifying direct sales. Texas also requires marketplace sales to be included when calculating the remote seller's safe-harbor amount.

New York goes further in illustrating why marketplace collection and seller registration are separate questions: marketplace sellers that independently meet vendor-registration requirements may still need to register and file even when the marketplace provider remits the tax on facilitated sales.

For detailed state marketplace rules, see Marketplace Facilitator Rules.

Marketplace sale vs direct sale

A merchant selling through both channels should track them separately.

Imagine the merchant has:

Marketplace sales: $400,000

Direct website sales: $150,000

into the same state.

The questions are not simply:

“Did we collect tax?”

The merchant needs to determine:

whether both channels count toward nexus;

whether the marketplace collected on facilitated sales;

whether direct sales create a merchant collection obligation;

how marketplace sales appear on the seller's return;

what documentation must be retained.

Different states answer those questions differently.

This is one reason sales by state and by channel should be part of the merchant's tax data model.

International online sellers can have U.S. sales-tax obligations

Being incorporated outside the United States does not automatically place a seller outside state sales-tax rules.

Economic-nexus regimes focus on the seller's activity in the state.

Texas explicitly provides a process for remote sellers located outside the United States to register to collect and remit Texas tax when required.

For an international merchant, U.S. launch preparation should therefore include:

identifying U.S. states receiving sales;

tracking sales by state;

understanding where inventory is located;

identifying employees, contractors, warehouses, or other physical connections;

distinguishing marketplace from direct transactions;

classifying products for state taxability;

monitoring economic-nexus thresholds.

The existence of a U.S. payment processor or U.S. dollar settlement account does not, by itself, answer those questions.

Payment flow and tax responsibility are related but separate.

The Online Sales Tax Decision Path

A merchant can organize the analysis through eight steps.

Identify the selling channel

Is the sale made:

on the merchant's own site;

through a marketplace;

through both?

Channel can affect collection responsibility.

Identify the state

Determine where the transaction is sourced under the applicable state's rules.

For many ecommerce transactions, the delivery destination is highly relevant, but sourcing rules should be confirmed state by state.

Determine nexus

Check:

Physical nexus

Does the seller have people, property, inventory, facilities, or another qualifying connection?

Economic nexus

Has the seller crossed the state's current remote-seller threshold?

Determine product or service taxability

Classify what is being sold.

Do not assume that:

all digital products;

all SaaS;

all clothing;

all food;

all services

receive identical treatment in every state.

Determine marketplace responsibility

If a marketplace facilitated the transaction:

Is the platform treated as a marketplace facilitator?

Is it responsible for collecting on this transaction?

Does the seller need documentation showing that collection occurred?

Does the sale still count toward the seller's nexus threshold?

Assess registration

If the merchant has a collection obligation:

What registration is required?

Which legal entity registers?

When must collection begin?

Does the merchant already hold a registration?

Calculate and collect

Only now determine:

taxable amount;

state rate;

applicable local rates;

customer exemptions;

tax shown at checkout.

File and remit

Maintain the return calendar and reconcile:

sales → taxable sales → collected tax → filed amount → remitted amount

This is the operational loop.

What online merchants should measure

Economic nexus is difficult to manage if the company cannot reliably see its sales by state.

At minimum, merchants should be able to monitor:

Sales by state

Track the sales amount using the measurement rules relevant to the state.

Transaction counts

Some states still use transaction counts as part of their nexus rules, while others have removed them. New York currently combines a sales and transaction test; Illinois removed its 200-transaction threshold beginning January 1, 2026.

Marketplace vs direct sales

The marketplace may collect on one channel while the merchant remains responsible on another.

Registered states

Know where each legal entity holds a sales-tax registration.

Filing status

Track whether each required return has been:

prepared;

filed;

paid;

reconciled.

The operational risk is not just failing to calculate the correct checkout amount. A merchant can correctly collect tax and still have incomplete registration, filing, or remittance processes.

What international merchants should prepare before launching in the U.S.

A merchant entering the United States does not need to solve every state's tax question on the first day if it will not initially have activity everywhere.

It does need an infrastructure capable of detecting when the questions become relevant.

Before launch, establish:

A state-level sales ledger

So nexus can be monitored.

A product-taxability model

So tax determination is not based only on the customer's ZIP code.

Channel identification

So marketplace sales and direct sales can be distinguished.

Physical-presence visibility

So inventory, warehouses, employees, and other activity are not invisible to the tax team.

Registration ownership

So someone knows who determines when a state registration is required.

Tax calculation capability

So state and local rates can be applied once responsibility is established.

Filing operations

So collected tax does not sit indefinitely in merchant accounts without being reported and remitted.

Change monitoring

Because state nexus rules, product taxability, rates, and marketplace rules can change.

Key takeaway

For online merchants, U.S. sales tax is not primarily a question of finding the correct percentage.

It is a sequence of jurisdictional decisions.

The merchant first needs to know:

Where did the sale occur for sales-tax purposes?

Then:

Do we have nexus?

Then:

Is this product or service taxable?

Then:

Who is responsible for collection—the merchant or a marketplace?

Then:

Do we need to register?

Only after those questions are resolved does rate calculation become the central problem.

That is why ecommerce businesses should build sales-tax readiness in this order:

Jurisdiction → Nexus → Taxability → Responsibility → Registration → Collection → Filing

For international sellers, the larger lesson is equally important:

Payment availability does not automatically equal tax readiness.

A U.S. checkout can be technically ready to process cards long before the merchant has determined where it has physical or economic nexus, how its products are treated, which marketplace sales alter responsibility, and which state registrations and returns will be required.

Map those obligations before they become launch-stage dependencies.

This article provides general information and does not constitute tax, legal, accounting, financial, or regulatory advice. Tax treatment depends on the merchant's circumstances, transaction structure, product or service, customer type, and applicable jurisdictions. Merchants should confirm their obligations with qualified tax and legal advisers and the relevant tax authorities.

FAQ

Do online merchants have to collect sales tax in every U.S. state?

No. Collection responsibility depends on factors including nexus, state law, the product or service sold, transaction sourcing, exemptions, and whether a marketplace is responsible for collection.

What is economic nexus for an online seller?

Economic nexus is a sufficient level of sales or other qualifying economic activity in a state that can trigger sales-tax registration and collection obligations even without traditional physical presence.

Is there one economic-nexus threshold for the United States?

No. State thresholds differ significantly. Current examples include California's $500,000 sales test, New York's combined $500,000-and-more-than-100-sales test, Texas's $500,000 remote-seller safe harbor, Florida's $100,000 remote-sales test, and Illinois's $100,000 threshold. The measurement rules also differ.

Does a marketplace collect sales tax for sellers?

In many states, qualifying marketplace facilitators are responsible for collecting and remitting tax on facilitated taxable sales. Sellers can still have separate obligations for direct sales, registration, filing, recordkeeping, or other activities depending on the state.

Do marketplace sales count toward economic nexus?

Sometimes. The answer is state-specific. California and Texas, for example, include qualifying marketplace sales in their remote-seller nexus calculations.

Can a foreign company have U.S. sales-tax nexus?

Yes. A seller does not need to be incorporated in the United States for a state's remote-seller rules potentially to apply. Texas expressly provides registration instructions for remote sellers located outside the United States.

Is sales-tax nexus the same as sales-tax registration?

No. Nexus describes the connection that can create a state's authority to impose a collection obligation. Registration is the administrative action that generally follows when the seller becomes required to collect.

Are all products taxed the same way?

No. Product and service taxability differs by state and sometimes locally. Pennsylvania exempts most clothing while taxing digital products generally, and New York has a specific clothing-and-footwear exemption structure for qualifying items below $110, with local variation.

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Sales Tax for Online Merchants: Nexus, Registration, and Marketplace Rules Explained

Meta title

Sales Tax for Online Merchants: Nexus & Marketplace Rules

Meta description

Learn how U.S. sales tax works for online merchants, including economic nexus, state thresholds, product taxability, marketplace rules, registration, collection, and filing.

Suggested URL slug

/sales-tax-for-online-merchants/

The editorial positioning below follows the supplied Tax & Invoicing brief, especially its requirement that this article own general U.S. ecommerce sales-tax mechanics and nexus, rather than becoming a detailed marketplace-facilitator guide.

Sources / research references

Primary research for this article was grounded in current guidance from the California Department of Tax and Fee Administration, including economic nexus and marketplace-facilitator rules.

For New York, the principal sources were the New York State Department of Taxation and Finance remote-seller nexus, marketplace, registration, and product-taxability guidance.

For Texas, the principal sources were the Texas Comptroller remote-seller, marketplace, local-tax, and filing guidance.

Florida remote-seller and marketplace claims were verified against the Florida Department of Revenue.

Illinois 2026 economic-nexus changes were verified against the Illinois Department of Revenue.

The Pennsylvania product-taxability example was verified against the Pennsylvania Department of Revenue.

tax calculation;

U.S. sales-tax determination;

marketplace tax handling;

sales-tax reporting;

tax registration support;

Merchant of Record tax collection.

Claims requiring tax/legal review

A qualified U.S. sales-tax specialist should review the final publication for:

the characterization of physical nexus;

the distinction between nexus and registration;

marketplace-seller residual obligations;

international remote-seller treatment;

state sourcing language;

examples involving product taxability;

the wording of any future state threshold examples added to the article.

The article intentionally avoids giving a universal rule for determining nexus, taxability, or registration because those questions are state- and fact-specific.

Date-sensitive claims to re-verify before publication

Recheck immediately before publication:

California's economic-nexus threshold and measurement basis;

New York's sales and transaction thresholds;

Texas's remote-seller safe harbor;

Florida's remote-sales threshold;

Illinois's $100,000 threshold and removal of the 200-transaction test;

marketplace-facilitator rules in any states specifically named;

New York's clothing exemption and local elections;

all product-taxability examples;

any filing-frequency or return requirements quoted;

any state thresholds added later.

This is one article where a last-reviewed date is editorially essential, because a threshold table can become misleading even when the underlying explanation remains sound.

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