Short answer: You must register for sales tax in a state the moment you establish nexus there — either physical (an employee, an office, or inventory in the state) or economic (crossing that state’s revenue or transaction threshold). Physical nexus triggers registration immediately or before your next taxable sale. Economic nexus starts its own clock, and the deadline is set by each state rather than by any common rule: some expect you to be registered before your next taxable sale into the state, while others give you a defined window after the period in which you crossed. It is worth confirming the deadline with the state directly, or talking to us about your situation, before you assume you have time in hand. Miss the deadline and penalties, interest, and personal liability accrue from the moment registration was due — not from when the state finds you.
If tracking 46 different threshold clocks across 46 different DOR portals isn’t how you want to spend the next six months, Sales Tax Compliance USA does the whole thing end-to-end for a single fee. No software for you to learn.
The Short Answer: When You Must Register for Sales Tax in Another State
Every US state that imposes a sales tax has its own registration trigger, its own threshold, and its own deadline. But every one of them follows the same two-step logic:
- You establish nexus — a legal connection to the state that gives it authority to require you to collect tax.
- You register — before your next taxable sale in the state, or within the state’s statutory deadline after nexus is established.
The exact position here depends on your own facts, so it is worth confirming with the state directly or talking to us about your situation.
- Physical nexus — one employee, one warehouse (including a third-party Amazon FBA fulfillment center), one contractor, one trade show that exceeds the de minimis carve-out, or in some states even a single delivery in your own vehicle.
- Economic nexus — you crossed a revenue or transaction threshold based on sales delivered into the state, even with zero physical footprint.
Since the US Supreme Court decided South Dakota v. Wayfair in June 2018. Every state that levies a general state sales tax has since enacted an economic nexus law of its own, each on its own terms and its own timetable. Missouri began requiring qualifying remote sellers and marketplace facilitators to collect and remit Missouri use tax on January 1, 2023. The five states with no general state sales tax — the NOMAD states — are New Hampshire, Oregon, Montana, Alaska, and Delaware, although Alaska has local sales taxes collected at municipal level.
Registration deadlines vary dramatically:
- California imposes economic nexus once combined sales of tangible personal property for delivery into the state exceed $500,000 in the current or preceding calendar year, at which point registration is required; exact timing depends on your facts. If you are approaching or have crossed the California threshold, contact us for a current review..
- New York requires sellers to register before beginning business, and a remote seller that meets both economic-nexus thresholds must register immediately and begin collecting tax as required.
- Washington gives you until the end of the month following the month you crossed.
- Most states default to “before your next taxable sale.”
Miss the deadline and the state’s clock keeps running against you. Interest and penalties accrue from the date registration was legally due — not from the date the state discovers you.
Two Types of Nexus That Trigger Registration (2026)
Physical Nexus: Employees, Inventory, Offices, Trade Shows
Physical nexus is instant and unforgiving. In every state with a sales tax, at least one of the following triggers registration immediately:
- An employee working in the state (even remotely from home)
- A contractor or agent soliciting sales on your behalf
- An office, warehouse, showroom, or storage facility
- Inventory stored in the state — including Amazon FBA warehouses
- Trade show attendance beyond the state’s de minimis carve-out
- Delivery of goods in your own vehicle
The Amazon FBA trap is real. This one varies by seller and by state, and it is the kind of detail we check for clients as part of the service — get in touch and we will confirm where you stand. When you ship inventory into the FBA network, Amazon distributes it across states without asking you and without telling you in advance. Every state where your inventory lands is a physical-nexus state for you.
Under California’s Marketplace Facilitator Act, a marketplace seller whose California sales are exclusively facilitated by a registered marketplace facilitator generally does NOT need a seller’s permit — even if inventory sits in California fulfillment centers, that physical presence alone does not trigger a registration obligation when 100% of CA sales are marketplace-facilitated (see CDTFA Marketplace Facilitator Act guidance)..
New York explicitly requires marketplace sellers to register for a Certificate of Authority even when all sales are made through a marketplace provider that collects sales tax on their behalf.
This is the single most misunderstood rule in US sales tax compliance for e-commerce sellers. “Amazon collects on my behalf, so I don’t need to register” is wrong in the states where you also store inventory.
Economic Nexus: Revenue and Transaction Thresholds
Post-Wayfair, all 45 sales-tax states plus DC have economic nexus laws. The typical threshold framework:
- $100,000 in sales OR 200 transactions into the state — the model South Dakota used in 2018, although South Dakota itself dropped the transaction prong with effect from July 1, 2023, so the two-prong wording you still see quoted around the web is frequently out of date
- Measurement period: prior calendar year, current calendar year, or a rolling 12-month period (state-specific)
- Several states have dropped the transaction-count prong entirely and now test on the sales figure alone
- A few outliers use higher dollar thresholds
Notable 2026 outliers you need to know:
- California — $500,000 in sales delivered into the state, no transaction prong
For the full state-by-state table, see our Economic Nexus Thresholds by State (2026) reference.
Click-Through, Affiliate, and Marketplace Nexus (2026 Status)
Click-through and affiliate nexus rules — the pre-Wayfair workarounds — have been largely superseded by economic nexus statutes. They still exist on the books in a few states but rarely bite anyone who’s already registered under economic nexus.
Marketplace nexus is the more important 2026 story. Every state with a sales tax has a marketplace facilitator law that shifts the collection duty to Amazon, eBay, Walmart, Etsy, Shopify, and similar platforms. But — and this is the trap — the marketplace collecting on your behalf does NOT eliminate your registration obligation in the states where you also have physical nexus. See our Marketplace Facilitator Laws by State guide for the full breakdown.
The Exact Moment the Registration Clock Starts: State-by-State Matrix
This is where most guides stop and we start. Every state has a threshold. Only some states clearly publish when the registration clock starts and how long you have to act after crossing it.
“Immediately” States
California registration timing is tied to crossing the state’s economic nexus threshold in the current or preceding calendar year, but the precise registration deadline depends on your specific facts. If you have recently crossed or are approaching the California threshold, contact us for a current review.. The California Department of Tax and Fee Administration takes the position that any taxable sale made after the threshold is crossed without a Seller’s Permit is an unregistered sale subject to full penalties.
Texas takes the same effective position — you must register before making a taxable sale in Texas once economic nexus is established.
“Within X Days” States
In practice, once your fourth-preceding-quarter sales and transactions cross both prongs of the conjunctive test, you should file for the Certificate of Authority immediately.
“Next Month” States
Washington and several other destination-sourced states operate on a “register by end of the month following the month you crossed” model. Rather than give you a figure that may not apply to you, we would check this against the state’s current guidance for your specific setup — ask us and we will tell you exactly where you stand.
Prior-Year vs Current-Year Measurement Periods
- Preceding calendar year only — you look at last year’s sales; if you crossed, you must register for the current year
- Current OR preceding calendar year — the more common model; either triggers registration
- Rolling 12 months — Texas and a small number of others; you must check monthly
California uses model 2 ($500,000 in the current or preceding calendar year). New York looks at the immediately preceding four sales tax quarters (a rolling model).
The practical consequence: if you’re near threshold in any state, you cannot check “did I cross last year” once in January and forget about it. You need monthly monitoring.
This is the specific work that our service does for you automatically — monthly nexus rollups against every state’s threshold, with alerts at 80% and mandatory registration when you cross.
How to Know You’ve Crossed a Threshold (Practical Tracking)
What Counts as “Sales” in the Threshold Calculation
This is the sneaky one. States define “sales” for nexus purposes in at least four different ways:
- Gross sales — all revenue delivered into the state, including exempt and wholesale (this is the broadest definition)
- Retail sales — excludes wholesale but includes taxable and non-taxable retail
- Taxable sales only — narrowest
- Sales of tangible personal property only — excludes services and digital products in some states
Most states use gross sales or retail sales. A minority use taxable-only. If you sell primarily wholesale into a state that measures gross sales, you can cross the threshold without owing a dollar of tax — and you still have to register.
Do Marketplace-Facilitated Sales Count Toward Your Threshold?
This is the single most under-covered question in DIY sales tax content.
- Marketplace sales count toward your threshold (most states) — Amazon, eBay, Etsy, Walmart, and Shopify Payments sales all count. Even if the marketplace collects the tax, those dollars push you over your own economic nexus threshold and can force you to register for your direct sales.
- Marketplace sales are EXCLUDED from your threshold (a growing minority) — some states have amended their statutes to exclude sales the marketplace already collected on, so only your direct sales count toward YOUR threshold.
- Ambiguous / evolving — a few states haven’t cleanly resolved this.
The list of states in each camp shifts as legislatures amend statutes. Rather than commit specific state assignments to writing here — because this changes frequently — contact us for a current review if you sell into a state where marketplace-vs-direct classification meaningfully affects whether you’ve crossed the threshold.
Do Wholesale and Exempt Sales Count?
Depends entirely on how the state defines the threshold measurement. In gross-sales states, yes. In taxable-sales states, no. Kansas and Oklahoma have historically counted wholesale sales; most states do not — but verify per state before assuming.
Monthly Nexus Review Checklist
Practical minimum for any multi-channel seller:
- Pull ship-to-state totals monthly from every sales channel (Shopify, Amazon, eBay, wholesale invoicing, direct-to-consumer)
- Reconcile against each state’s specific definition of “sales” for threshold purposes
- Alert at 80% of threshold in any state
- Register and begin collecting the moment you cross
Or let us run this monthly rollup for you and eliminate the possibility that you miss a threshold and find out via a state audit letter 18 months later.
What If You Already Crossed the Threshold Months Ago? (Retroactive Exposure)
If you’re reading this and realising you probably had nexus in five states a year ago, you’re in the retroactive-exposure conversation. There are three paths forward and they matter in that specific order.
Option 1: Register Now and Backfile
Best when:
– Exposure is small (under about $10,000 in back tax per state)
– The exposure is recent (under 12 months)
– You want to move fast and are willing to pay standard late-filing penalties and interest
Mechanics: register today, file all missed returns back to your nexus-established date, pay tax plus penalty plus interest. Most states will impose late-filing and late-payment penalties (commonly 10% of tax due plus interest at the state’s published rate).
Option 2: Voluntary Disclosure Agreement (VDA)
Best when:
– Back-tax exposure exceeds $10,000 in a state
– You crossed thresholds more than 12 months ago
– You need penalty abatement to make the numbers work
– You want to negotiate the lookback period rather than accept all-history exposure
VDAs are formal agreements between a taxpayer and a state DOR. The taxpayer voluntarily comes forward, and in exchange the state limits the lookback (typically 3 to 4 years) and waives most or all penalties. Interest usually still applies but is often reduced.
California operates both an In-State and an Out-of-State Voluntary Disclosure Program through the CDTFA, with a typical three-year lookback and penalty waiver for cooperative disclosure.
New York’s Voluntary Disclosure and Compliance Program does not guarantee a standard three-year lookback; the lookback period is discretionary, requested in the application, and determined case-by-case, with penalties waived for the agreed period (see NYDTF VDA lookback guidance). Eligibility generally requires that the taxpayer is not under audit and has not been billed for the taxes being disclosed..
For deeper mechanics, see our Voluntary Disclosure Agreement guide.
Option 3: Wait (Rarely Advisable)
Waiting is only defensible when:
– You’re actively winding down US operations
– You’re absolutely below threshold going forward and expect to stay there
– You’ve stopped shipping inventory into physical-nexus states
Not sure how this applies to your business? We handle US sales tax registration, filing and remittance for ecommerce sellers as a fully managed service, for one fee. Book a free consultation and we will review your own position with you.
Critical warning: the statute of limitations on assessment does NOT run for unregistered sellers in most states. If you never file a return, the state has no return to audit and no clock has started. When they find you — via marketplace data sharing, VAT-registration cross-referencing, or a tip — they can go back to the first day of your nexus.
This is the single most important sentence in this article: failing to register does not eventually protect you. It permanently extends your exposure.
How to Estimate Your Back Tax Liability
The rough math per state:
- (Taxable sales into the state since nexus date) × (average state combined rate ~7%) = base tax
- Add 10-25% penalty depending on state
- Add interest at the state’s published rate compounded from due dates
- For VDA scenarios, subtract most or all penalty
If you’re staring at multi-state retroactive exposure and don’t know where to start, book a consultation — we do this exposure-quantification exercise as the first step of every VDA engagement.
Which States to Register in First (Prioritization Framework)
If you’re behind in more than three or four states, you cannot register everywhere on Monday. You need a prioritization framework.
Tier 1: Register Immediately
- Your home state — always, regardless of revenue, if you have any physical presence
- Any state where you have physical inventory today (FBA warehouses, 3PLs)
- Any state where you have employees or contractors
- The top three to five states by revenue where you’ve clearly crossed economic nexus
Tier 2: Register This Quarter
- Additional states where you’ve clearly crossed economic nexus
- Aggressive-audit states where your revenue is meaningful — California, New York, Washington, Texas, and Illinois consistently show up on practitioner lists as more active enforcers
- Any state that has already contacted you (a nexus questionnaire, an information request, a marketplace data-share letter)
Tier 3: Monitor
- States where you’re between 80% and 100% of threshold with static growth
- States where you’re clearly under threshold and marketplace-facilitated
Rank by Penalty Severity
Some states have more painful penalty regimes. Louisiana’s parish-level administration multiplies compliance cost. Colorado’s home-rule cities each impose their own tax on top of state tax. Alabama’s Simplified Sellers Use Tax (SSUT) program simplifies things for remote sellers but is a specific opt-in.
Special Case: Home State First
Your home state gets registered first because you have physical nexus there by definition, and because home states share information with your income-tax and franchise-tax registrations. Getting caught unregistered in your home state is a bad look with your state legislature, your bank, and any future business buyer doing due diligence.
The Special Cases: Foreign Sellers, No EIN, No US Bank Account
If you’re a non-US founder — Amazon FBA seller in the UK, Australia, New Zealand, or South Africa; Shopify brand shipping DTC into the US; SaaS founder based in Ireland or Singapore selling to US customers — this section is for you.
Registering Without a US EIN
You cannot register for sales tax in most states without a Federal Employer Identification Number (EIN). Even the states that accept SSNs for sole proprietors will not accept a foreign national’s tax ID from Canada, the UK, or elsewhere.
The path forward:
- Obtain an EIN using IRS Form SS-4. Foreign entities without an SSN or ITIN cannot use the online EIN application — you must fax or mail Form SS-4 to the IRS, or call the international EIN line
- Once you have your EIN (typically 4-6 weeks by fax; longer by mail), you can register in state portals
For the full walkthrough, see our How to Get an EIN as a Foreign Business guide.
Registering Without a US Bank Account
Many state portals require a US bank account for ACH direct-debit of tax payments. As a foreign seller, your options:
- Open a US business bank account (Mercury, Wise Business, or a traditional US bank with a foreign-owned entity relationship)
- Use a payment intermediary or agent-service in states that permit third-party payment
- Pay by credit card in the states that accept it (with convenience fees)
Amazon FBA Foreign Sellers
The specific playbook for a UK, Australian, or South African FBA seller with US inventory:
- Confirm which states hold your inventory (Amazon Seller Central Inventory Reports show fulfillment center locations)
- Register in every state where inventory is stored, regardless of your revenue
- Register in every additional state where you’ve crossed economic nexus
- File monthly or quarterly returns, reporting marketplace-facilitated sales as non-taxable and remitting tax only on direct sales
This is the exact done-for-you engagement we run for cross-border sellers. See our US Sales Tax for Foreign Sellers guide and our Amazon FBA nexus breakdown.
States That Are Foreign-Seller Friendly vs Difficult
Foreign-friendly registration environments in 2026 (relative terms):
– Washington — clean single-state portal, accepts foreign entities
– Florida — recent portal upgrades, foreign-seller path exists
– Most SST member states — Streamlined Sales Tax simplifies multi-state registration
More difficult for foreign sellers:
– Louisiana — parish-level administration means multiple registrations per state
– Colorado — home-rule cities each impose separate registration
– Alabama — SSUT helps but requires specific opt-in
– California — the state itself is fine, but the volume and complexity of California-specific rules is highest in the country
If you’re a non-US founder registering across five or ten states, the cost-benefit of DIY collapses very quickly. Our service exists specifically to handle this without you learning fifty state portals.
After Registration: What Comes Next (Filing, Remittance, Deregistration)
Assigned Filing Frequency
Every state assigns a filing frequency at registration — typically monthly, quarterly, or annual — based on your projected tax liability. New registrants often default to quarterly. If your actual liability turns out higher, the state will move you to monthly (sometimes with prepayment requirements).
California’s CDTFA assigns filing frequency based on reported or anticipated tax liability, and accounts with estimated tax averaging $17,000 or more per month are placed on a quarterly prepayment schedule (see CDTFA prepayment guidance)..
New York does not default all registrants to quarterly filing: certain manufacturers/wholesalers expecting no tax due may be registered as annual filers, quarterly filers with $3,000 or less in tax across the four most recent quarters may be reclassified to annual, and monthly filing is required once combined taxable sales/use in any quarter reach $300,000; PrompTax is a separate program for vendors with taxable receipts over $500,000 (see NY Filing Requirements for Sales and Use Tax Returns)..
Zero Returns Are Still Required
The single most common way registered sellers get automatic penalties: forgetting that a registered account requires a return every period even if you had zero sales into the state. Missing zero returns triggers automatic late-filing penalties — often a $50 minimum per return regardless of whether tax was owed.
Trailing Nexus: When You Can Stop Filing
Once you drop below threshold, you cannot immediately deregister. Most states require continued filing through the end of the current calendar year plus at least the following calendar year — a “trailing nexus” period. Some states require formal proof that you’re below threshold before permitting deregistration.
For the state-by-state breakdown, see our Trailing Nexus guide. Trailing periods vary and depend on specific facts — if you need to close a registration, contact us for a current review.
Proper Deregistration
You do not close a sales-tax registration by simply not filing. You must:
- File a final return for the closing period
- Pay all outstanding tax, penalty, and interest
- Submit a formal account closure or surrender form to the DOR
- In some states, obtain a tax clearance certificate before closing
Just stopping filing without formal closure keeps the account open, keeps penalties accruing, and can create personal-liability exposure for officers and members.
Do-It-Yourself vs Done-For-You: Honest Comparison
The True Cost of DIY Multi-State Registration
Here is the actual DIY cost for a seller with nexus in ten states:
- Learn each of ten state portals — average 4 to 8 hours per state including account creation, EIN verification, bank verification, and answering state-specific business questions
- Assemble supporting docs (formation docs, EIN letter, officer identification, projected sales) — 2 to 4 hours
- File the ten registration applications — 1 to 2 hours per state
- Respond to any state follow-up questions (typically 3 to 5 of the 10 states will come back with clarifications) — 2 to 5 hours each
- Set up filing calendars, portal login management, and reminder systems — ongoing
Total realistic time: 60 to 100 hours of qualified operator time. That’s before you file your first return.
What Automated Sales-Tax Software Alone Cannot Do
The major sales-tax software platforms are good at one thing: automating filing AFTER you’re already registered. They generally do not:
- Handle initial multi-state registration end-to-end
- Handle VDA negotiations across multiple states
- Register foreign-owned entities with the state-specific documentation problems those entities face
- Respond to state follow-up questions on your behalf
- Coordinate marketplace-facilitator sales reporting across states with different treatment rules
Software is a tool you have to learn and operate. That’s their model and their pricing reflects it.
How Our Service Works
Sales Tax Compliance USA is a full-service engagement, not software you have to run yourself:
- Nexus assessment — we run your monthly sales data against every state’s threshold and every physical-presence trigger, identify where you’re already required to register, and quantify any retroactive exposure
- Registration package — we file the registration applications in every state where you have nexus, handle EIN and bank-verification questions, and respond to state follow-up questions
- VDA where needed — for states with material back-tax exposure, we run the VDA process with the state DOR anonymously until terms are agreed
- Ongoing filing and remittance — monthly, quarterly, or annual returns filed in every registered state, tax remitted from your account, filing calendar managed by us
- Audit defence — if a state audits, we handle it
One intake. One flat fee. A tax practitioner (Paul le Roux, CA(SA)) reviews every registration. No software for you to learn. No 50 portals for you to log into.
If you’d rather not spend the next six months learning fifty state DOR websites, book a free consultation or see what’s included in our full service.
Frequently Asked Questions
How many states do I need to register for sales tax in?
Only the states where you have nexus — physical or economic. For a typical Shopify or Amazon FBA seller doing $1M-$5M in annual US revenue, this is usually 5 to 25 states. Below $1M, often 3 to 10 states. Above $10M, typically 30 to 45 states.
Do I need to register in a state if I only sell through Amazon FBA?
Yes, in every state where Amazon stores your inventory, because the inventory creates physical nexus that is independent of the marketplace-facilitator collection rules. California and New York explicitly state this in published guidance. Marketplace-only sellers with no inventory in a state generally do not need to register in that state.
What happens if I don’t register for sales tax when I should have?
Tax, penalty, and interest accrue from the date registration was legally due. Because you never filed a return, the statute of limitations on assessment does not run — the state can go back to the first day of your nexus when they find you. Officers and members can be personally liable for unremitted trust-fund sales tax under most states’ responsible-person statutes.
How long do I have to register after crossing an economic nexus threshold?
Varies by state. Immediately in California and Texas. At least 20 days before beginning operations in New York. End of the month following the month you crossed in Washington. Before the next taxable sale in most other states. Specific deadlines depend on state and fact pattern — if you’ve recently crossed a threshold, contact us for a current review.
Do wholesale or exempt sales count toward the economic nexus threshold?
Depends on the state’s specific definition. Gross-sales states include wholesale; retail-sales states exclude wholesale; taxable-sales states exclude both wholesale and exempt retail. Most states use gross or retail sales. Verify per state before assuming.
Can a foreign (non-US) business register for US state sales tax without an EIN?
Almost never. Every state that requires an EIN for entities will require one for foreign entities too. Foreign businesses obtain EINs via Form SS-4 by fax or mail to the IRS. See our How to Get an EIN as a Foreign Business guide.
Do I need to register in every state or just the ones where I have physical presence?
Physical presence AND economic nexus each independently require registration. A seller with no physical presence but who has crossed the economic nexus threshold in a state must register in that state. A seller with physical presence (including FBA inventory) in a state must register there regardless of revenue.
What is the statute of limitations for unregistered sales tax liability?
For registered sellers who filed returns, most states have a 3 to 4 year statute of limitations on assessment. For unregistered sellers who never filed, the clock generally does not start — meaning the state can assess back to the first day of nexus indefinitely, or subject to a much longer limit. This is why voluntary disclosure agreements exist.
Should I register retroactively or do a Voluntary Disclosure Agreement?
Rough threshold: under about $10,000 in back tax per state, standard retroactive registration and backfile is usually fastest. Over $10,000 per state or with exposure going back more than a year, a VDA typically pays for itself in penalty savings and lookback limitation. Full analysis in our VDA guide.
How much does it cost to register for sales tax in multiple states?
State registration fees themselves are usually zero or nominal (under $100 per state in most states). The real cost is operator time — 6 to 10 hours per state for DIY, or a single flat fee for a full-service engagement. Our sales tax registration service quotes are based on the number of states and complexity of your fact pattern.
Last verified: 2026-07-07.
This article is for informational purposes only and does not constitute tax advice. Consult a licensed tax professional before acting on any of this content.
