How does the SST program simplify sales tax compared to non-member states?
SST member states are structurally cheaper for qualifying sellers: registration, calculation, and filing are covered through a Certified Service Provider at no charge to the seller. Brands with significant SST-state nexus should choose a CSP platform to capture this benefit — non-CSP platforms charge full rate regardless of which states you're filing in.
The 24 SST member states have agreed to a common set of standards designed to make sales tax simpler for multi-state sellers. Non-member states, including major markets like California, Texas, New York, and Florida: each have their own rules, and compliance in those states requires navigating each state’s individual requirements.
Understanding the difference helps you know where the complexity actually lives in your nexus footprint, and where there’s cost relief you may not be capturing.
What SST states agree to
SST member states have adopted a model statute that standardizes several of the most frustrating aspects of multi-state sales tax:
Uniform definitions. SST states use consistent definitions for key product categories, food, clothing, medicine, digital goods. A product that qualifies as “food” in one SST state uses the same definition across all SST member states. Non-SST states define these categories independently, which is part of why product taxability is such a state-by-state puzzle.
Destination-based sourcing. SST states all use the ship-to address to determine which rate applies. Non-SST states vary, some use origin-based sourcing, some use destination, some have hybrid rules, which creates calculation complexity across channels.
Centralized registration. SST sellers can register in all 24 member states simultaneously through the SST Central Registration system in a single application. Non-SST states each require their own registration process, their own portal, and in some cases their own form of identification.
Certified Service Providers. The SST program created the CSP framework: a mechanism for qualifying sellers to get registration, calculation, filing, and remittance funded by the state rather than the seller. Non-SST states have no equivalent. Every filing in a non-SST state costs the seller money directly.
What the cost difference looks like
| SST state (with CSP enrollment) | Non-SST state | |
|---|---|---|
| Registration | Handled through SST Central Registration; cost covered | State-by-state; fees vary ($0–$100+) |
| Calculation | Covered by CSP program for qualifying sellers | Software cost; your responsibility |
| Filing | $0 for qualifying sellers enrolled through a CSP | Charged by your platform or CPA ($42–$75/return typical) |
| Remittance | Handled by CSP | Your responsibility |
| Audit liability | CSP holds audit liability for SST-covered calculation errors | On the seller |
For a qualifying remote seller enrolled through a CSP platform, SST states cost nothing to file in beyond the base platform fee. Non-SST states each carry a per-filing charge.
A seller with 10 SST states and 5 non-SST states, filing monthly, might pay nothing for the 10 SST filings and $42–$75 per period for the 5 non-SST filings, roughly $2,520–$4,500/year for the non-SST portion alone.
The 24 SST member states
| Arkansas | Indiana | Nebraska |
| Georgia | Iowa | Nevada |
| Kansas | Kentucky | New Jersey |
| Michigan | Minnesota | North Carolina |
| North Dakota | Ohio | Oklahoma |
| Rhode Island | South Dakota | Tennessee |
| Utah | Vermont | Washington |
| West Virginia | Wisconsin | Wyoming |
Note that several large ecommerce markets (California, Texas, Florida, New York, Illinois) are not SST members. Your compliance costs in those states are unaffected by SST enrollment.
Where the SST program doesn’t help
Non-SST states remain fully your cost. Texas, California, Florida, and New York are among the highest-volume states for most ecommerce sellers, and none are SST members. Filing fees in those states are charged regardless of your CSP enrollment status.
SST only applies to qualifying remote sellers. If you have physical presence in an SST state (employees, inventory, an office) you likely don’t qualify as a remote seller in that state and the CSP compensation doesn’t apply. Physical nexus states are treated like non-SST states for cost purposes.
Product complexity doesn’t disappear entirely. SST states use standardized definitions, which reduces complexity. But the definitions themselves still require you to classify your products correctly under the SST framework, and some categories (digital goods, bundled products) still have state-level variation even within SST.
Why some sellers don’t realize they’re missing SST benefits
The main reason: their sales tax platform isn’t a CSP, or is a CSP but doesn’t proactively maximize SST enrollment for customers.
TaxJar is not a CSP — SST enrollment is simply not available to their customers. Avalara is a CSP but charges per-state filing fees even for SST states, capturing the state compensation as platform revenue rather than passing it to the customer. Sellers on those platforms pay for SST-state filings even when they don’t have to.
See: Why won’t Avalara and TaxJar tell me about SST benefits? for the full explanation of why this happens.
Frequently asked questions
Which states are SST member states?
Is filing in SST member states free?
What is a Certified Service Provider (CSP) in the SST program?
Why do some platforms not pass SST savings to sellers?
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