Comparison and adjacent
SST states vs non-SST states: what you still owe
Simplify Sales Tax. Last updated 2026-09-01. Sources last verified 2026-09-01.
The Streamlined Sales Tax (SST) program reaches 24 of the 45 states with a general sales tax. In the other 21, nothing about it applies. You owe tax wherever your nexus puts you either way, but outside the member states you register on that state’s own form, source that state’s rates yourself, and file on that state’s terms.
If you sell nationally you are running both processes at once. This page is about which jobs stop at the membership line and which do not.
Which states are in the Streamlined program, and which are not?
Twenty-four are in: 23 full members and Tennessee as the only associate member. The complete list, with each state’s status and joining date, is on the member state list.
Of the 50 states, 45 levy a general sales and use tax, and the Governing Board’s own count is that twenty-four of those forty-five have passed the conforming legislation. So 21 states with a general sales tax have not adopted the Agreement, and five states levy no general sales tax at all.
None of that is a judgment about the 21. A state outside the program administers its own sales tax under its own law, exactly as it always has.
What changes in an SST member state, and what does not change anywhere
Table: what a seller with nexus on both sides of the Streamlined membership line runs in each half. Checked September 1, 2026.
| What you are running | In one of the 24 member states | In one of the other 21 |
|---|---|---|
| Whether you owe tax at all | Your nexus in that state decides it, under that state’s own rules | Identical. Membership changes nothing about this |
| Whether the shared registration reaches it | Yes, for whichever member states you tick in it. See how to register | No. Never, not partially, and nothing you do in the shared system reaches it |
| How you get registered | One application covers any or all of the member states you select | That state’s own form, one state at a time |
| Where your rates come from | The state builds and publishes them free to any business, and holds you harmless where you relied on its data | You. You source and maintain them, with no equivalent program commitment behind you |
| What you have to learn per state | One shared library of defined terms. You still read each state’s own taxable-or-exempt answers | Each state’s own categories, learned separately |
| What you file | One return per period per state, covering every jurisdiction inside it, in a uniform format the full member states accept. See the Simplified Electronic Return | That state’s own return, in that state’s own system |
| Who audits you, and who they call | One state level authority for the state and its localities, and the states take audit contact to a qualifying seller’s provider. See audits with a CSP | The state, and a locality may separately. No equivalent program commitment |
| What you already owed there | Unchanged. Registering settles nothing backwards, and amnesty is the only thing that reaches back, on its own conditions | Unchanged, and no program route reaches it |
| Who pays for the filing work | The states fund a certified provider where you meet the CSP-compensated seller criteria in that state | Nobody. Anything a provider does is ordinary paid work on commercial terms |
The first row is the one to read twice. Membership changes how you comply. It doesn’t change whether you have to.
Does Streamlined registration cover a state that is not a member?
No. Not partially, not by extension, not later.
The shared registration system is a system the member states built for their own registrations. Selecting states in it selects from the 24. A state outside the program never appears in it, and nothing you do there creates, updates, or satisfies a registration anywhere else.
This is the fact most worth knowing on this page, because the mental model people arrive with is that one registration handles the country. It handles a defined 24, and you register in the rest the way you always did.
What do you still owe in the other 21 states?
Everything you owed before, on the same terms.
If your nexus reaches a non-member state, that state can require you to register, collect, file, and remit under its own law and on its own cadence. It sets its own rates, defines its own categories, runs its own audits, and takes its own return. The Governing Board keeps a state by state guide to remote seller requirements covering all 50 states, and its own note on that chart is that nothing in it overrides an individual state’s laws.
Joining the program doesn’t settle anything you already owed there, and it doesn’t settle anything you already owed in a member state either. What reaches backwards is amnesty, which has its own conditions and its own exclusions.
What about Alaska, Delaware, Montana, New Hampshire and Oregon?
Alaska, Delaware, Montana, New Hampshire, and Oregon levy no general sales tax, so there’s no state sales tax registration to hold and nothing for the program to simplify.
One clause, because “no general sales tax” is not always “nothing to collect.” Alaska’s own state assessor says the state does not levy a sales tax and that several local municipalities do, so you can carry a local obligation there with no state return anywhere in the picture. Oregon runs a narrow use tax on vehicles, and Delaware taxes business gross receipts rather than transactions. Treat the absence of a general sales tax as the fact, and check the specifics with the state before assuming a channel is clear.
Do certified providers cover the other 21 states, and on what terms?
They usually do, and you pay for it.
The states fund a certified provider’s work in member states where you meet the CSP-compensated seller criteria, and that funding stops at the membership line. Everything a provider does for you in the other 21 is ordinary commercial work on ordinary commercial terms. Four of the six publish something on this and they agree in shape. Sovos states that its fees apply only to non-SST states, states where eligibility criteria are not met, and additional value-added services. TaxCloud states that a subscription is what supports compliance in non-SST states. Avalara publishes one plan with the state-funded services and one without. AccurateTax publishes registration and compliance coverage across the states generally.
The practical version is that your provider bill tracks the half of your footprint the states don’t pay for, so it grows with your non-member states rather than with your member states. Who qualifies is on who qualifies for state-funded provider services.
Two boundaries. A provider figure is that provider’s own claim about its own coverage, and the Governing Board’s number for the program is 24. And these extracts were retrieved before this page was written, so check a provider’s current published terms before you rely on any of them.
What this does not fix: you are still running two processes
Splitting the map in two is a description, not a plan, and the honest limitation of this page is that the two halves never converge.
- None of the program’s protections cross the line. The hold harmless on state data, the uniform definitions, the one-return rule, the audit routing: all of it stops at the 24.
- The count is the whole argument. Two member states in your footprint gets you very little and you still run the other process for everything else. Fifteen gets you a lot. That arithmetic is the enrollment decision.
- A provider doesn’t erase the line either. What the states fund stops at the 24, and the rest is bought. See the section above.
The outcome to plan for is one compliance process with a simplified 24-state core and an unchanged remainder, not one process everywhere. If most of your states are members that core is most of your work and the program is worth the obligation it creates. If two of them are, you have bought an obligation in two states and changed nothing about the rest.