The Streamlined Sales Tax (SST) program is a multistate agreement that standardizes how member states handle sales tax registration, filing, and collection. Established in 2005, SST has been adopted by 23 states, plus one associate member. If you're a business selling into those states, SST replaces a patchwork of separate registrations and filing portals with a single system.

More than 35,000 businesses have registered through SST's single portal, with nearly 30% of them using a Certified Service Provider (CSP) to handle calculation and remittance.

Below, we’ll cover what SST standardizes, which states participate, which major markets sit outside it, and where the program's coverage ends.

Key takeaways

• With SST, sellers have one registration form and filing system across 23 member states (plus Tennessee’s associate membership), instead of separate processes for each.

• Some of the largest retail markets in the country haven’t joined SST. National sellers still need a separate compliance approach for those states.

• Volunteer sellers without nexus in a member state can register anyway, and often get the cost of a CSP covered by the state.

What is the Streamlined Sales Tax (SST) program?

The Streamlined Sales Tax program is a multistate agreement that standardizes how member states handle sales tax collection. Member states agree on uniform product definitions (e.g., “clothing” or “food” means the same thing everywhere), a single registration form that covers every member state at once, and one electronic filing system instead of a separate portal for each state.

Which states participate in Streamlined Sales Tax?

Twenty-three states hold full membership in the Streamlined Sales Tax program. Tennessee holds associate status, meaning it has adopted much of the agreement but hasn’t yet reached full conformity. Some of the largest retail markets in the country, including California, Texas, Florida, New York, Illinois, Colorado, and Pennsylvania, are not part of the program.

Here’s each state’s membership status:

How does Streamlined Sales Tax simplify compliance for online sellers?

Streamlined Sales Tax cuts down sales tax compliance work using five specific mechanisms.

Here’s how it works:

• Uniform definitions: Member states agree on standard definitions for categories such as clothing, drugs, and food and food ingredients, so a business doesn’t have to check what counts as food in every state it sells into.

• Single registration: The Streamlined Sales Tax Registration System (SSTRS) lets a seller register once and get sales tax accounts in every member state at the same time, instead of filing a separate application with each state’s department of revenue.

• One filing system: Sellers file through the Simplified Electronic Return (SER), a standardized form every member state accepts, rather than using a different online portal for each jurisdiction.

• Destination-based sourcing: Member states apply the same sourcing rule for many transactions. They tax sales at the delivery address instead of mixing origin and destination rules the way nonmember states sometimes do.

• State-funded technology: Member states supply rate and boundary databases and cover part or all of the cost of a CSP for qualifying sellers. That way, getting the rate right for a given address doesn’t fall entirely on the seller’s own systems.

Who should register through the Streamlined Sales Tax program?

Streamlined Sales Tax distinguishes between nonvolunteer and volunteer sellers, which changes both cost and obligation.

Nonvolunteer sellers

A nonvolunteer seller already has nexus (a legal duty to collect tax) in an SST member state. That duty might come from physical presence (e.g., office, warehouse, employee) or from economic nexus, which kicks in once a seller crosses a state’s sales or transaction threshold (e.g., $100,000 in a calendar year). These sellers already have to register and collect in that state whether or not SST exists. SST gives them a faster, more consistent way to do it across every member state instead of state by state.

Volunteer sellers

Although a volunteer seller doesn’t have nexus in a given member state, it registers there anyway to stay ahead of growth or keep its compliance approach consistent across its state footprint. Member states typically cover the cost of using a CSP for these sellers, since the state ends up collecting tax on sales it wouldn’t have seen otherwise.

How do you register and file under Streamlined Sales Tax?

Registration runs through the SSTRS portal. One form is required no matter how many member states a seller intends to register in.

Here are the steps:

• Choose a filing method: Sellers pick between a CSP, which handles calculation and remittance directly, Certified Automated System (CAS) that the seller integrates and manages in a more hands-on way, or filing returns manually using the state-provided rate tables.

• Complete the SSTRS application: The form asks for business identification details, states the seller intends to register in, and chosen filing method. Registration through SSTRS doesn’t carry a fee.

• Set an effective date: Sellers choose when registration and the collection obligation start. Starting at the beginning of a filing period, rather than mid-month, can simplify compliance.

• File the SER: Once registered, sellers submit SER filings on the schedule each state assigns, usually monthly or quarterly depending on sales volume. Filing happens through the same system across every member state where they’re registered.

• Remit collected tax: Payment goes out alongside each SER filing. The CSP or filing software routes funds to the right states based on where the sales happened.

What are the limitations of the Streamlined Sales Tax program?

SST doesn’t cover you in every state, eliminate audit exposure or other tax obligations, or automate exemption handling.

Here’s what falls outside the scope of SST, which you’ll still need to handle separately:

• Sales tax in nonmember states: A seller doing business nationally still needs a plan for the states outside the Streamlined Sales Tax program.

• Audit exposure: Sellers using a CSP get some liability protection when a CSP calculates tax incorrectly, but the seller still owns the accuracy of the product and transaction data feeding that CSP. Audits of that underlying data can still happen.

• Other taxes: Income tax, franchise tax, and business licensing requirements sit outside SST’s scope. A business registered for sales tax through the program still has to track those obligations separately in each state where it operates.

• Exemption handling: Resale certificates and exemption documentation still need to be collected and validated, even though SST standardizes the certificate format across member states.

A tool such as Stripe Tax calculates and collects tax across all 50 states and internationally, tracks where a business has crossed an economic nexus threshold, and applies the correct rate and rules whether or not the state in question participates in SST.

How Stripe Tax can help

Stripe Tax reduces the complexity of tax compliance so you can focus on growing your business. Start collecting taxes globally by adding a single line of code to your existing integration, clicking a button in the Dashboard, or using our powerful API.

Stripe Tax helps you monitor your obligations and alerts you when you exceed a tax registration threshold based on your Stripe transactions. It can also register to collect tax on your behalf in the US, automate US filings in the Dashboard, and manage global filings through trusted partners. Stripe Tax automatically calculates and collects sales tax, VAT, and GST on:

• Digital goods and services in all US states and over 100 countries

• Physical goods in all US states and 42 countries

Stripe Tax can help you:

• Understand where to register and collect taxes: See where you need to collect taxes based on your Stripe transactions. After you register, switch on tax collection in a new state or country in seconds. You can start collecting taxes by adding one line of code to your existing Stripe integration, or add tax collection with the click of a button in the Stripe Dashboard.

• Register to pay tax: If you need to register for sales tax in the US, let Stripe manage your tax registrations. You’ll benefit from a simplified process that prefills application details—saving you time and simplifying compliance with local regulations. If you need help registering outside of the US, Stripe partners with Taxually to help you register with local tax authorities.

• Automatically collect tax: Stripe Tax calculates and collects the right amount of tax owed, no matter what or where you sell. It supports hundreds of products and services and is up-to-date on tax rules and rate changes.

• Simplify filing: Stripe Tax automates US filings in the Dashboard, powered by TaxJar. For global filings, Stripe Tax seamlessly integrates with filing partners, so your global filings are accurate and timely. Let our partners manage your filings so you can focus on growing your business.

Learn more about Stripe Tax, or get started today.