What is a Certified Service Provider (CSP) and why does it matter?
A Certified Service Provider is a company formally certified by the SST Governing Board to deliver compliance under the program. Only CSPs can offer free filing in SST states — the states compensate them directly, so qualifying remote sellers pay nothing. As of May 2026 there are five active CSPs: TaxCloud, Avalara, Sovos, Avior, and AccurateTax. TaxJar, Numeral, and Kintsugi are not CSPs.
A Certified Service Provider is a company that has been formally certified by the Streamlined Sales Tax Governing Board to deliver compliance services under the SST program. CSP status isn’t a marketing claim, it’s a specific designation administered by the multi-state body that runs the program, with a public roster of who holds it.
The reason it matters for sellers: only CSPs can offer free filing in SST states.
How the CSP compensation model works
When a seller enrolls in the SST program through a CSP, the CSP handles registration, calculation, filing, and remittance in all SST member states where the seller has nexus. The CSP is not compensated by the seller for this work in SST states, it’s compensated by the states themselves.
SST member states agreed to fund the cost of compliance for enrolled remote sellers in exchange for reliable, monthly collection from sellers who would otherwise be non-compliant. The states pay a portion of collected revenue to the CSP as compensation for delivering that compliance.
The result: a qualifying remote seller enrolled through a CSP pays nothing for SST-state compliance, not per filing, not per registration, not per state.
Who the five CSPs are
As of May 2026, the SST Governing Board’s public roster lists five companies as actively offering services under the program:
| Provider | Notes |
|---|---|
| TaxCloud | Purpose-built for ecommerce sellers; specifically positions SST enrollment as core to its service |
| Avalara | Enterprise-focused; SST enrollment available but not prominently featured for SMB/mid-market customers |
| Sovos | Enterprise compliance platform; SST services primarily for large enterprise |
| Avior | Smaller provider; primarily serves specific verticals |
| AccurateTax | Smaller provider; SST services available |
The roster is public and updated by the Governing Board. Verify current status at streamlinedsalestax.org.
What non-CSP providers can and can’t do
Non-CSP providers — TaxJar, Numeral, Kintsugi, and most other sales tax software companies, can provide sales tax calculation, nexus monitoring, and filing services. They can file in SST states. What they cannot do is deliver the SST program’s free-filing benefit, because they are not parties to the state compensation arrangement.
A seller filing monthly in 10 states (7 of which are SST members) through a non-CSP provider pays per-filing fees for all 10 states. Through a CSP, the 7 SST states cost nothing. Over a year filing monthly, that’s 84 returns that were free vs. charged.
Why some CSPs don’t lead with this
Avalara is a CSP. But SST enrollment reduces its per-filing revenue from enrolled sellers in SST states. It’s not in Avalara’s commercial interest to aggressively surface SST enrollment to existing customers. Sellers enrolled through Avalara are often paying per-state filing fees for SST states they could be getting for free.
This is why the question “why won’t my provider tell me about SST?” comes up often. The financial incentive to disclose SST eligibility proactively doesn’t exist for most providers.
Related: Why won’t Avalara and TaxJar tell me about SST benefits?
Frequently asked questions
What is a Certified Service Provider (CSP)?
Which companies are currently Certified Service Providers?
Is TaxJar a Certified Service Provider?
Why does CSP status matter for sellers?
Does it cost more to use a CSP?
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