Streamlined Sales Tax glossary

This glossary defines the Streamlined Sales Tax (SST) terms this site uses. The SST program runs on a small vocabulary, used precisely by the people who wrote it and loosely by nearly everyone else. That gap is where the trouble starts. A CSP is not a CAS, and being a Model 1 seller is not the same thing as being a seller the state pays for. Every term below is defined against primary sources, and where a term is commonly misused, you’ll find the misuse noted with it.

The program

These terms set what the program is, which states are in it, and what a state’s membership status changes for you.

Streamlined Sales Tax (SST) A cooperative effort among 24 US states to simplify and standardize sales tax administration and reduce the cost of complying across state lines. Started in March 2000. If you are working out whether any of it reaches your filings, start with what the SST program is.

Streamlined Sales and Use Tax Agreement (SSUTA) The agreement member states adopt into their own law. It sets the simplification requirements: uniform definitions, centralized registration, simplified rates, standardized sourcing, and the rest. The Agreement is the rulebook, and the Governing Board administers it. What you read in a member state’s own statute is that state’s adoption of it.

Streamlined Sales Tax Governing Board (SSTGB) The body that administers the Agreement, certifies service providers, and publishes the program’s authoritative material. Not a federal agency, and not a tax authority. It does not assess or collect tax, so nothing you owe is owed to it.

Full member state A state that has brought its sales tax laws into compliance with all the requirements of the SSUTA. There are 23. The program has 24 states in total, but 23 is the count to size against when you’re working out where you can qualify for free CSP services, because Tennessee’s treatment is unresolved.

Associate member state A state that has brought its laws into line with the SSUTA but doesn’t yet have all of its statutory or rule changes in effect, or that complies with nearly all of the Agreement rather than all of it. Tennessee is the only one. The distinction matters more than it looks: several program mechanics that apply automatically in full member states are qualified or unavailable in an associate member state. Whether free CSP services apply in an associate member state has no published answer, which is why this site counts 23 rather than 24. What associate status changes has the three mechanics that turn on it, and if Tennessee sits in your footprint, check the one you are relying on instead of assuming it carries over.

Amnesty Relief from uncollected tax, interest, and penalties for prior periods, available to a seller registering in a state within a defined window after that state joins the program. The window has closed in the full member states, and Tennessee is the only state currently offering amnesty. Registering through the SSTRS does not relieve prior liability except where amnesty applies, so exposure you are already carrying comes with you.

Providers

These are the terms readers collapse into each other most often. Each entry says where the term stops.

Certified Service Provider (CSP) SSUTA Section 203 defines it as “An agent certified under the Agreement to perform the seller’s sales and use tax functions as outlined in the contract between the Streamlined Sales Tax Governing Board and the Certified Service Provider, other than the seller’s obligation to remit tax on its own purchases.” Six are certified. That contract, not the provider, is what defines the functions a CSP takes on for you. See what a CSP is.

Certified Automated System (CAS) Certified software that determines the tax due on a transaction. A CAS is a system. A CSP is an agent that operates one on your behalf and takes on the associated functions. The two are often used interchangeably and should not be, so when you are told something is certified, the question to ask is certified as which one.

CSP-compensated seller A seller that meets all five criteria in the CSP Operating Contract in a given state, which makes that state compensate the CSP for the certified services there. The test is applied per state, which means you can hold it in one state and not in another, and you can lose it where you stop meeting the criteria. See the CSP-compensated seller test.

Volunteer seller The former term for CSP-compensated seller. Still widely used in older material and in some state guidance. If you see it, read it as CSP-compensated seller and check the criteria, which are what actually govern.

Model 1 seller A seller that has contracted with a CSP to perform its sales and use tax functions. Being a Model 1 seller and being a CSP-compensated seller are two different things. The contract makes you Model 1. The five criteria, per state, determine whether the state pays.

Model 2 seller A seller using a Certified Automated System to determine tax, while remaining responsible for filing and remitting.

Model 3 seller A seller with sales in at least five member states and at least $500 million in total annual sales revenue, using its own proprietary system under a performance agreement with the member states. A performance agreement is not certification: certification is what a Certified Automated System or a Certified Service Provider gets.

Model 4 seller A seller registered through the program that is not using Model 1, 2, or 3. Self-filing.

Registration and filing

The mechanics you actually touch once you are in.

Streamlined Sales Tax Registration System (SSTRS) The single system for registering for sales tax in member states. Registration through it is free, though individual states may charge where you are legally required to register there. See how to register.

Registration date The date your collection and filing obligation begins in a state you registered in. It cannot be changed after submission, so the date you put in is the date you live with.

Simplified Electronic Return (SER) A uniform electronic return accepted by full member states. Tennessee allows it only for remote sellers with no Tennessee business location. See what a Simplified Electronic Return is.

Sourcing The rule determining which jurisdiction’s tax applies to a sale. Destination sourcing applies the rate where the purchaser receives the item. Origin sourcing applies the rate at the seller’s location. The Agreement standardizes sourcing for sales between states, but it permits member states to elect origin sourcing for sales within their own borders, so “uniform sourcing” is uniform interstate and not always intrastate.

Rate and boundary database Files each member state publishes mapping addresses to jurisdictions and rates. Sellers and providers that use them correctly get relief from liability for a rate error caused by the state’s own data.

Taxability matrix A document each member state publishes stating how it taxes the Agreement’s uniform product definitions. It is how you find out whether a given category is taxable in a given state without reading the statute.

Certificate of compliance A member state’s own statement of how it complies with each provision of the Agreement.

Adjacent terms

Terms that sit outside the program and get pulled into conversations about it.

Economic nexus The obligation to collect a state’s sales tax once sales into that state pass its threshold, without any physical presence. Established for sales tax by South Dakota v. Wayfair (2018). Separate from SST, and the two interact: the Governing Board states that a seller required to collect in a state only because it crossed that state’s economic nexus threshold qualifies for free CSP services there. That is the Board’s position on nexus, not a shortcut past the rest of the test, so the seller still has to meet the CSP-compensated seller criteria. The two documents behind that are separated on how SST and economic nexus interact.

Marketplace facilitator A platform that collects and remits sales tax on behalf of third-party sellers using it. A separate regime from SST, with its own state-by-state rules. What a mixed-channel seller still owes is on SST and marketplace facilitator laws.

Taxability Information Code (TIC) A code identifying a product or service category for taxability determination.

Each term above links to the page that works it out where this site has one. If you’re starting from the beginning, that’s what the SST program is.