How do I register for SST through a Certified Service Provider?

SST registration goes through your Certified Service Provider, not directly with individual states. You provide your business information and the SST states where you have nexus; your CSP submits the unified registration to the SST Governing Board on your behalf.

Step 1: Confirm you qualify

The SST free-filing benefit applies to remote sellers: those without physical nexus in the state. You’re a remote seller in an SST state if you have no employees, no inventory, and no other physical presence there. Your obligation comes from economic activity alone (crossing the threshold) or from SST enrollment.

If you have physical nexus in some SST states, those states may still be covered by SST enrollment, but discuss with your CSP how physical-nexus SST states are handled and whether any fees apply.

Step 2: Identify your nexus SST states

Before your CSP can register you, you need to know which SST member states you have nexus in. The 24 SST member states are listed at Which states are SST member states?.

For each state where you have nexus:

• Your nexus start date: the date you crossed the economic nexus threshold, or the date physical presence began
• Whether the nexus is economic or physical: relevant to how your CSP handles the state

If you haven’t done a nexus analysis, do that first. Registering in states where you don’t have nexus creates unnecessary compliance obligations. Missing states where you do have nexus creates gaps your CSP can’t cover.

Step 3: Contact a Certified Service Provider and initiate enrollment

The five active CSPs as of May 2026 are TaxCloud, Avalara, Sovos, Avior, and AccurateTax. Each has its own onboarding process, but the SST enrollment step is handled by all of them.

When you contact your chosen CSP:

• Tell them you want to enroll in the SST program
• Provide the list of SST states where you have nexus and your start date in each
• Complete their business verification requirements (typically EIN, legal name, contact information)

Step 4: Your CSP submits the Central Registration application

Your CSP submits a registration application to the SST Governing Board through the Central Registration System. The application includes:

• Your business identification (legal name, EIN, address)
• The SST member states being registered
• Your nexus effective date in each state
• The CSP designation, identifying your CSP as the authorized filer

The SST Governing Board processes the application and notifies each SST state. Each state creates your account and designates your CSP as the authorized agent.

Step 5: Confirm active registration in each state

Your CSP will notify you as registrations are confirmed by individual states. Processing times vary, some states confirm within days; others take 2–4 weeks. Your CSP tracks this and will give you confirmation when each SST state is active.

Until a state confirms your registration, your CSP cannot file there. If your nexus has been active for some time and you have unfiled prior periods, discuss with your CSP how those periods will be handled, whether that means a VDA for the prior period or a direct retroactive filing.

Step 6: CSP takes over all SST-state compliance

Once your SST registrations are active:

• Your CSP handles tax calculation in SST states at point of sale (or post-transaction, depending on integration)
• Your CSP prepares and files monthly returns in all your SST states
• Your CSP remits the collected tax to each state
• The state compensates your CSP; you pay nothing for these states

Your role is to ensure your sales data flows accurately to your CSP’s system, and to notify your CSP when you have nexus changes, new SST states crossed, product line additions, or changes in physical presence.

What about non-SST states?

SST registration only covers the 24 SST member states. For non-SST states — California, Texas, New York, Florida, Illinois, and others where you have nexus, you register directly with each state and your CSP charges per-filing fees for those states. Your CSP typically handles non-SST registration as part of onboarding as well.