How does a CSP's audit liability shield work in SST states?

The CSP audit liability shield is one of the most concrete compliance benefits of SST enrollment, and one no Avalara or TaxJar customer gets in non-SST states. Understanding exactly what it covers (and what it doesn’t) helps sellers evaluate the real risk transfer.

What the shield covers

When a seller uses a CSP to calculate sales tax in SST member states, the SST program’s governing agreements create a liability transfer for CSP-caused errors:

Covered: Tax miscalculations that result from errors in the CSP’s rate database, product taxability rules, or calculation logic. If the CSP applies the wrong rate to a correctly classified transaction, and the seller remits what the CSP calculated, the state’s remedy is against the CSP, not the seller.

The mechanism: SST member states agree not to assess liability against sellers for calculation errors attributable to CSP reliance, provided the seller gave the CSP accurate transaction data. The CSP is required to indemnify the state or cure the calculation error.

What the shield does not cover

The shield is limited to the CSP’s contribution to the compliance process. Seller-side errors remain the seller’s liability:

• Incorrect product tax codes: if the seller assigns the wrong PTC to a product and the CSP calculates correctly based on the wrong PTC, the liability stays with the seller
• Missing nexus registration: if the seller has nexus in a state but hasn’t registered and isn’t filing, the CSP shield doesn’t help: the seller isn’t using the CSP in that state
• Invalid exemption certificates: certificate management is the seller’s responsibility; accepting a fraudulent or invalid certificate and exempting a sale doesn’t transfer to the CSP
• Inaccurate transaction data: if the seller provides wrong information (wrong ship-to address, wrong transaction amount), the CSP’s calculation based on that data doesn’t trigger the shield

Why this matters for B2B sellers

For sellers with significant exempt sales, the certificate-side of compliance remains fully on the seller. But for the calculation side, particularly in complex multi-rate states like Georgia, North Carolina, or Tennessee: the CSP shield means an auditor finding a rate error charges the CSP for correction, not the seller.

This is a material difference from using non-SST-certified software or self-filing. In non-SST states or with non-CSP software, all calculation errors belong to the seller.

SST states where the shield applies

All 24 current SST member states. Non-SST states (CA, TX, FL, NY, AZ, CO, IL, and others) do not have CSP program equivalents, so the shield doesn’t apply there regardless of which software the seller uses.