Sales Tax 101: What Every U.S. Business Needs to Know

Sales tax is a type of tax that U.S. states charge on the sale of goods and some services. Sales tax is only applied at the final point of sale to the consumer and is not collected throughout the supply chain, and your business is responsible for collecting that tax and remitting it to the state. But here’s the tricky part: sales tax rules are different in every state. Some states charge it, some don’t, and each has its own rules about when and how to collect it.

Whether or not you need to collect sales tax depends on something called “nexus.” Nexus refers to a business’s connection to a particular state. This connection can be physical, such as having a warehouse, office, or employee in the state, or it can be economic, based on reaching a certain threshold of sales or transactions within that state. Even if your business is fully online and based outside the U.S., you may still have economic nexus if you sell a lot to customers in certain states.

So, who needs to collect sales tax? If your business meets a state’s nexus rules, no matter whether you’re selling on Amazon, Etsy, Shopify, or even your own website, you’re generally required to register with that state, collect the correct sales tax rate, and file regular returns.

It may sound overwhelming, but knowing when and where to collect sales tax is a big step toward staying compliant and avoiding penalties down the line.

A sales tax permit, also known as a seller’s permit or sales tax license, is a state-issued authorization that allows your business to collect sales tax from customers. It is required in states where your business has nexus and sells taxable goods or services.

To obtain a sales tax permit, you must apply through the state’s Department of Revenue (or equivalent agency). The application process typically involves providing basic business information such as your EIN, business structure, physical address, a description of your products or services, and estimated sales volumes. Some states issue the permit immediately online, while others may take a few days to process.

Keep in mind that each state has its own rules, fees, and registration requirements. Operating without a required permit can result in penalties, so it’s important to register before collecting any sales tax.

Nexus refers to the level of connection your business has with a particular U.S. state that creates a legal obligation to collect and remit sales tax there. If your business has nexus in a state, you’re required to register for a sales tax permit and collect sales tax from customers in that state.

There are two main types of nexus:

Understanding where you have nexus is critical for staying compliant. If you fail to register and collect sales tax where you have nexus, you could face fines, penalties, or audits, even retroactively. That’s why it’s important to regularly review your sales activity and understand each state’s nexus rules.

Economic nexus is a sales tax rule that requires businesses to collect and remit sales tax in a state based on their economic activity there, even if they have no physical presence in that state. This rule was established after the 2018 U.S. Supreme Court decision in South Dakota v. Wayfair, Inc., which allowed states to enforce sales tax collection from remote sellers.

Economic nexus is typically triggered when your business exceeds a certain threshold of sales revenue or number of transactions within a state over a 12-month period. These thresholds vary by state. For example, many states set the limit at $100,000 in sales or 200 separate transactions, while others may have different standards or only use revenue as the basis.

If you meet a state’s economic nexus threshold, you are legally required to:

This rule mainly affects e-commerce and remote sellers, especially those selling through platforms like Amazon, Etsy, or Shopify. Monitoring your sales by state is essential to ensure you’re compliant with each jurisdiction’s laws.

Physical nexus is established when your business has a tangible connection to a state. This type of nexus has long been the traditional basis for sales tax obligations and is still widely enforced across the United States.

You may trigger physical nexus in a state if your business:

If you meet any of these conditions, you’re typically required to:

Even if you’re a remote seller, using fulfillment centers like Amazon FBA can create physical nexus in multiple states, depending on where your goods are stored. That’s why it’s essential to track where your inventory and personnel are located to avoid non-compliance.

Use tax is a companion to sales tax. It applies when you buy a taxable item without paying sales tax, usually from out-of-state or online sellers, and then use, store, or consume that item in your home state. It ensures states still collect tax revenue even if the seller didn’t charge sales tax at the point of purchase.

The main difference is:

For example, if you purchase office equipment from an online retailer that doesn’t charge your state’s sales tax, you may be required to report and pay use tax directly to your state.

Businesses are often audited for unpaid use tax, so keeping track of untaxed purchases is essential for staying compliant.

A Resale Certificate is a document that allows a business to purchase goods without paying sales tax, as long as those goods are intended for resale. Instead of being the end consumer, your business acts as a middle party that buys products to later sell to customers.

When you present a resale certificate to a supplier, you’re confirming that:

Each state has its own format, and some accept out-of-state certificates under reciprocity rules. In most cases, you’ll need a valid Sales Tax License to issue one. Misusing a resale certificate (e.g., for buying office supplies) can result in fines and penalties.

Resale certificates are especially common in e-commerce, wholesale, and retail businesses where products pass through multiple sellers before reaching the final buyer.

A resale certificate allows your business to purchase goods intended for resale without paying sales tax at the time of purchase. If you’re in the business of reselling physical products, whether through an online store like Amazon, Etsy, or Shopify, or through a retail location, you likely need to obtain one.

Most U.S. states require businesses to have a resale certificate if they want to buy inventory tax-free. To get a resale certificate, you generally need to have a valid sales tax permit in the state where you’re doing business. Once registered, you’ll provide the certificate to your suppliers to confirm that the products you’re purchasing are for resale.

Some states don’t issue a separate resale certificate. In those cases, your sales tax permit or number serves the same function. It’s important to understand the specific requirements in each state where you operate or have nexus, as using a resale certificate incorrectly can lead to penalties or back taxes.

If you regularly buy goods for resale, registering for a resale certificate helps you stay compliant and avoid unnecessary tax costs.

A resale certificate allows your business to purchase goods without paying sales tax, as long as those goods are intended for resale. This can be a major advantage for retailers, wholesalers, and e-commerce sellers who regularly buy inventory.

Key Benefits Include:

It's important to keep in mind that you can only use a resale certificate when buying items for resale. Using it for business supplies, equipment, or personal items is not allowed and may lead to penalties or audits.

Using a resale certificate properly can save your business money and simplify your purchasing process. Just be sure to follow the rules for your state.

A Sales Tax License (also called a Seller’s Permit or Sales Tax Permit) gives your business the legal authority to collect sales tax from customers in a specific state. You must apply for it through the state’s tax agency before selling taxable goods or services. It’s the foundational document for sales tax compliance.

A Resale Certificate, on the other hand, allows you to purchase goods tax-free if you plan to resell them. Instead of paying sales tax on inventory or wholesale purchases, you give your supplier a resale certificate to show you’re not the end consumer.

Here’s the key difference:

You usually need a Sales Tax License before you can issue a valid Resale Certificate. Many states require you to include your license number on the certificate.

Yes, in most states, resale certificates are not valid forever and must be renewed periodically. The renewal timeline and rules vary by state, so it’s important to understand your specific obligations.

For example:

If you use an expired resale certificate, you could be held liable for sales tax on your purchases, even if you resold the items. Some vendors may also refuse to accept your certificate if it’s out of date.

Tip: Even if your state doesn’t require formal renewal, keep your certificate details up to date and be ready to provide a new form when requested by vendors.

To collect and remit sales tax in a U.S. state, you must first register with that state’s tax authority and obtain a Sales Tax Permit (also known as a seller’s permit or sales tax license). This is a legal requirement for businesses that have sales tax nexus in a state, whether physical or economic.

While the application process can change depending on the state, the general steps remain similar:

Need help registering in multiple states? Clemta can assist with streamlined, state-by-state registrations and ongoing sales tax compliance.

If you sell products or services online through platforms like Shopify, Etsy, Amazon, or your own website, you may need to collect sales tax from buyers depending on where your business has nexus. To do this, you first need to register for a sales tax permit in the states where you’re required to collect tax. Once registered, you can enable sales tax collection within your e-commerce platform’s settings by selecting the appropriate states and, in some cases, entering your permit number.

Most major platforms will automatically calculate the right tax rate at checkout based on the customer’s location. If you’re selling in multiple states, it’s helpful to use tax automation tools to keep up with rate changes and filing requirements. Always make sure to keep clear records of the taxes collected and ensure your filings are submitted on time to avoid penalties. Proper setup and compliance not only help you avoid legal issues but also build credibility with customers.

You need to start charging sales tax as soon as your business establishes nexus in a state and you’re selling taxable goods or services there.

For example, if you’re selling on Amazon and have inventory stored in one of its fulfillment centers in Texas, you likely have nexus in Texas. Or, if you’re selling through Shopify and hit $100,000 in sales to customers in Illinois, you likely have economic nexus there.

Once you’re registered in a state, you must:

Most e-commerce platforms like Shopify, Amazon, and Etsy allow you to automatically calculate and collect sales tax. If you’re issuing manual invoices, make sure to apply the appropriate state rate and include your sales tax permit number for transparency.

Keeping clean, detailed records of your sales, tax collected, and invoices will make state filings easier and help avoid compliance issues.

Sales tax rates in the U.S. vary not just by state, but also by county, city, and even district. That means the total tax rate a customer pays depends on their exact location, not just the state they live in.

If you’re selling online, the rate is usually based on the destination address. This is called destination-based sourcing, and it applies in most states.

To calculate the right sales tax rate:

Some platforms automatically update tax rates based on ZIP codes, but ZIP codes don’t always match tax boundaries perfectly. Using address-level sourcing is more accurate.

If you’re invoicing manually, it’s best to double-check rates using an official source or sales tax software. Always keep documentation in case of an audit.

Whether you need to collect sales tax on digital products or services depends entirely on the state where your customer is located. Each state has its own rules about what qualifies as a taxable digital good or service.

As a general rule of thumb, digital products and services may be subject to sales tax depending on the state where your customer is located, and the specific type of digital good you’re selling.

Some states only tax permanent downloads, while others also include subscriptions, streaming, or cloud-hosted access in their definitions. Always check the rules for the specific states where you have nexus, as the definitions and taxability vary widely.

Because these rules vary so much, the safest approach is to:

Even if your product is digital, once you cross a nexus threshold in a state, you may be required to register and collect tax on those digital goods or services if that state considers them taxable.

You only need a sales tax permit in states where your business has nexus, which is a connection that requires you to collect and remit sales tax. This connection could be:

For example, if you sell on Amazon and have inventory stored in a fulfillment center in Florida, you likely have physical nexus there and need a permit. Or if you make over $100,000 in sales to customers in New York through your Shopify store, you likely have economic nexus in New York and must register.

You do not need to register in states where you have no nexus. However, it’s essential to regularly review your sales and activities to determine if you’ve triggered nexus in new states, especially as your business grows or expands to new platforms.

To register for sales tax in multiple U.S. states, follow these general steps:

1. Determine Where You Have Nexus

First, identify the states where you’ve triggered nexus, either physically (office, employee, inventory) or economically (meeting a sales threshold like $100,000 or 200+ transactions). You only need to register in those states.

2. Decide How to Register

You can register:

3. Prepare Required Information

You’ll typically need:

4. Submit Applications and Track Approvals

Once approved, you’ll receive a Sales Tax Permit or registration number. Keep track of your filing frequency and deadlines for each state, as the deadlines may differ.

5. Begin Collecting and Remitting

After registration, you must begin collecting the correct sales tax on sales in that state and filing returns on time.

As you expand, regularly reassess your nexus footprint to ensure you’re registered in all necessary states.

Selling taxable goods or services without a valid sales tax permit can lead to serious consequences. If a state discovers you’ve been operating without one, they may charge back taxes, penalties, and interest on any uncollected sales tax. Even if you didn’t know you were supposed to collect it, you’re still legally responsible.

Some states may consider this tax evasion, especially if it continues over time, which can lead to fines or legal action. Additionally, failure to comply could hurt your chances of getting permits or licenses in the future.

To avoid issues, always check whether you need to register in a state before making sales there, especially if you sell online across state lines.

The frequency with which you need to file sales tax returns depends on the state and how much sales tax you collect. States typically assign a filing frequency when you register for a sales tax permit, and this schedule can be monthly, quarterly, or annually.

Filing frequencies can also change with time. If your business grows and you collect more tax, the state may reassign you to a more frequent schedule.

Make sure to check your filing due dates on your state’s tax portal and keep reminders to avoid penalties. Even if you haven’t made any taxable sales in a period, many states require that you file a zero return to stay compliant.

Missing a sales tax filing deadline can result in penalties, interest charges, and even loss of good standing with the state’s Department of Revenue.

Most states charge a late filing penalty, usually a percentage of the tax due, plus daily or monthly interest until the return is submitted. Even if you didn’t collect any sales tax during the filing period, failing to file a zero return can still lead to penalties.

In some cases, repeated late filings may result in additional scrutiny or audits.

What to do if you missed the deadline:

To avoid this in the future, consider setting calendar reminders or using sales tax software that automatically tracks deadlines for each state where you’re registered.

If you sell across multiple platforms (like Amazon, Etsy, Shopify, or your own website), you still need to file one combined sales tax return per state where you’re registered. That means you must report all sales made to customers in that state, regardless of the platform used.

To do so, you can follow the steps below:

States like California, New York, and Texas require platforms like Amazon or Etsy to collect and remit sales tax for you. However, you still must report those sales in your return, even if no payment is due.

To file your sales tax return, you’ll typically need to access your account on the state’s Department of Revenue website. From there, you’ll report key figures such as your total gross sales, taxable sales, and the amount of tax you’ve collected. In some cases, you may also need to break down these figures by sales channel, especially if some of your platforms (like Amazon or Etsy) are marketplace facilitators that collect tax on your behalf. After reviewing and confirming the details, you can submit your return and make any payments due by the state’s filing deadline.

Using accounting tools or sales tax software can help automate this process and reduce the risk of errors.

For proper sales tax compliance, it’s important to maintain detailed and organized records. These records should include:

States can audit businesses for several years back (often 3–7 years), so it’s a good idea to securely store these records for at least that long. Digital bookkeeping software or cloud storage can help you stay organized and audit-ready.

Yes, most major marketplaces like Amazon, Etsy, eBay, and Walmart are required by law to collect and remit sales tax on behalf of their sellers. This is due to Marketplace Facilitator Laws adopted in almost all U.S. states. When you sell through these platforms, they usually handle the sales tax collection for customer orders shipped to states where such laws apply.

However, this doesn’t mean you’re off the hook entirely. You may still have sales tax obligations such as registering in certain states, filing periodic returns, or reporting sales made outside of the marketplace (for example, through your own website). Even when the marketplace collects tax, you are ultimately responsible for ensuring your business stays compliant. It’s important to keep an eye on sales data and tax reports provided by each platform to make sure everything aligns with your broader tax responsibilities.

Amazon and Etsy are considered marketplace facilitators, meaning they are legally required in most states to collect and remit sales tax on your behalf for orders shipped to those states. You don’t need to collect the tax yourself, but you should still monitor the sales and tax reports they provide, and depending on the state, you may need to file “zero return” reports or include marketplace sales in your filings.

Shopify, on the other hand, is not a marketplace. It’s an e-commerce platform. That means you are fully responsible for collecting, reporting, and remitting sales tax. Shopify gives you the tools to set up tax collection based on your nexus and product types, but it won’t handle filings for you unless you integrate a third-party app like TaxJar or Avalara.

Each platform has its own rules, tools, and responsibilities, so make sure to review how your store is set up and what’s required of you based on your nexus and where your customers are located.

Marketplace Facilitator Law is a rule that requires certain online platforms, like Amazon, Etsy, eBay, and Walmart, to collect and remit sales tax on behalf of the third-party sellers who use their platform.

Before these laws, individual sellers were responsible for collecting and remitting sales tax on each sale. Now, if a marketplace facilitator has nexus in a state (which they often do), the platform becomes responsible for handling sales tax, not the seller.

This means that if you’re selling through one of these platforms, you generally don’t have to collect or remit sales tax yourself for orders made through them in states with marketplace facilitator laws. However, you may still need to register for a sales tax permit and file returns, especially if you also sell on your own website or through other channels.

Most U.S. states have enacted marketplace facilitator laws, so it’s important to understand your obligations even if the platform handles part of the process.

In most cases, you do not need to collect U.S. sales tax on international orders. U.S. sales tax is generally only required when goods or services are sold to customers located within the United States, and the seller has established nexus in that specific state.

If your buyer is located outside the U.S., for example, in Europe or Asia, and you are shipping goods abroad, that sale is typically considered outside the scope of U.S. sales tax.

However, it’s important to:

If you also sell within the U.S., make sure you’re collecting the proper sales tax for domestic orders while clearly separating international sales in your records.