The 2018 Supreme Court decision in South Dakota v. Wayfair fundamentally changed how sales tax applies to multi-state commerce. Before Wayfair, a business needed physical presence in a state (an office, employees, warehouses, or inventory) to be required to collect that state's sales tax. After Wayfair, states can impose sales tax collection obligations based on "economic nexus", a threshold of sales volume or transaction count into the state, regardless of physical presence. A small e-commerce business selling $100,000 per year into any given state almost certainly has sales tax nexus there, often requiring registration, collection, filing, and remittance in dozens of states.
The compliance complexity is real. Each state sets its own thresholds, rates, taxability rules, and filing frequencies. Forty-five states plus D.C. have sales tax; thresholds range from $100,000 in sales or 200 transactions (the common pattern) down to lower levels in a few states. A small business with modest interstate sales can easily trigger nexus in 10-20 states without realizing it, each requiring its own registration and ongoing compliance. The good news: the solution is tooling (sales tax automation software) and process, not avoidance, ignoring nexus obligations eventually produces back-tax assessments, penalties, and interest that can dwarf the original compliance cost.
What Creates Sales Tax Nexus
Multiple activities can trigger nexus in a state.
| Nexus Type | Trigger | Typical Threshold |
|---|---|---|
| Physical Nexus | Office, warehouse, employees, inventory | Any level |
| Economic Nexus | Sales volume or transaction count | $100K/200 transactions (common) |
| Click-Through Nexus | Affiliate referrals from in-state parties | Varies by state |
| Marketplace Nexus | Selling via Amazon, Etsy, etc. (platform may collect) | N/A for seller if platform collects |
| Inventory Nexus | Product stored in state (e.g., Amazon FBA warehouse) | Any stored inventory |
| Trade Show / Temporary Presence | Temporary in-state activity | Varies by state |
The Economic Nexus Patterns
Post-Wayfair, most states adopted similar economic nexus rules with variations.
Standard Pattern
$100,000 in gross sales OR 200 separate transactions in the previous or current calendar year. About 30 states use this pattern. Triggering either threshold creates nexus; losing the threshold doesn't immediately eliminate nexus (typically requires a full year below).
Higher Thresholds
A few states use $500,000 (California, New York, Texas) or unique thresholds. Smaller states sometimes use $100,000 without the 200-transaction trigger (so low-ticket high-volume sellers avoid nexus). Know your target states' specific thresholds.
Measurement Period
Some states measure previous 12 months; others measure current calendar year; others measure both. The measurement detail matters when approaching thresholds, a seller just under $100K might cross mid-year in current-year measurement states but not in prior-year states.
Marketplace Facilitator Relief
Most states now require marketplace platforms (Amazon, Etsy, eBay, Walmart) to collect sales tax on behalf of third-party sellers. If all your interstate sales go through these platforms, your direct sales tax exposure is substantially reduced, the platforms handle collection and remittance. Direct-to-consumer sales via Shopify, WooCommerce, or direct channels don't get this relief.
The Compliance Reality
Multi-state sales tax compliance is complex enough to justify automation for most sellers.
For each state where you have nexus: (1) Register for sales tax permit (one-time, typically free or small fee). (2) Determine taxability of your products in that state, taxability rules vary (software, SaaS, digital downloads, clothing, groceries, and services have especially variable treatment). (3) Determine rate, states have state-level rate plus county, city, and district rates, a single state can have hundreds of distinct tax jurisdictions. (4) Collect tax at checkout at the correct rate based on customer location. (5) File sales tax returns at the required frequency (monthly, quarterly, or annually depending on volume). (6) Remit tax collected on time, penalties for late filing/payment start immediately. Doing this manually across 10+ states is practically impossible, tools like Avalara, TaxJar, and Anrok automate most of this for monthly fees ($200-$1,000 depending on scale) and are worth the cost for any serious multi-state seller.
Florida-Specific Considerations
Florida sellers have specific home-state obligations plus multi-state exposure.
Florida Sales Tax Basics (Home State)
- 6% state rate plus county discretionary sales surtax (0-1.5%)
- Most services are NOT taxable (Florida is one of few states)
- Tangible personal property is taxable unless exempted
- Remote sellers have FL nexus at $100K threshold (enacted 2021)
- Monthly or quarterly filing depending on volume
- Florida's DR-15 return filed through FL DOR online system
Outbound Multi-State Exposure
- Most Florida sellers have nexus in 5-15 states without realizing it
- Software (SaaS) taxability varies by state, complex
- Digital products and downloads taxed differently across states
- Shipping fees sometimes taxable, sometimes not
- Tax-exempt customers (resellers, nonprofits) require certificate management
- Automation tool subscriptions typically pay for themselves by the second state
The Voluntary Disclosure Path
For businesses that discover past nexus non-compliance.
- Most states offer Voluntary Disclosure Agreements (VDAs), come forward, pay limited back tax, avoid penalties
- VDAs typically limit look-back to 3-4 years (vs. unlimited exposure otherwise)
- Penalties typically waived under VDA; interest usually still owed
- Must approach the state BEFORE they contact you, lose VDA eligibility after state inquiry
- Work with state tax specialist; each state has different VDA procedures
- Alternative: wait and hope (risky, state discovery triggers full exposure including penalties)
- Register going forward even if not filing back returns, stops future exposure accumulation
- Professional advice important, VDA paperwork complexity varies by state
Sales tax nexus is one of the most consequential compliance areas for small businesses selling across state lines, and one of the most commonly overlooked. Post-Wayfair, a small business with any meaningful interstate sales likely has nexus somewhere, often in many somewhere. The compliance work is substantial but manageable with the right tools: sales tax automation software handles rate calculation, collection, and filing for monthly fees that are small relative to the liability they prevent. The single highest-leverage move for any small business with interstate sales is to run a nexus analysis: where do you sell, where have you crossed thresholds, where do you need to register. From there, implementing automation and remediating past non-compliance is a structured process. Ignoring the issue, by contrast, builds liability quietly until discovered, and discovery can produce back-tax bills that threaten the business.
Before subscribing to full sales tax automation, run a simple nexus analysis: list all states with sales shipped-to in the previous 12 months, with total dollar volume and transaction count by state. This spreadsheet (accessible from any e-commerce platform report) identifies which states exceed thresholds. Many businesses discover they have clear nexus in 2-3 states and are approaching it in 5-10 more. This prioritization lets you register and automate in order of exposure, rather than trying to solve everything at once.
Frequently Asked Questions
Depends on the state. Florida generally doesn't tax services (a few exceptions). Many states tax specific service categories (data processing, telecommunications, certain personal services). Hawaii and New Mexico have broad gross receipts taxes that function like sales tax on services. Rule varies substantially, check each state's specific rules if you provide services cross-state.
Most states now require the platform (Amazon, Etsy, eBay, Walmart) to collect and remit sales tax as a "marketplace facilitator." Sellers on these platforms often have substantially reduced direct sales tax obligations. Direct sales through Shopify, WooCommerce, and own-website channels are still the seller's responsibility. Mixed sellers (some marketplace, some direct) still need to track direct sales for nexus purposes.
No. Sales tax is a state-level tax, not federal. Each state's department of revenue enforces independently. The IRS is not involved. State discovery typically comes through: audits of customers who bought from you, 1099-K data from payment processors that states access, outreach campaigns, or voluntary reporting by businesses that had your products reported as exempt purchases.
Entry-level automation (TaxJar, Quaderno): $100-300/month. Mid-range (Avalara, Taxify): $500-2,000/month for meaningful scale. Enterprise solutions can be much more. For any business with 5+ nexus states and meaningful sales volume, automation is essentially required and almost always pays for itself. For very small sellers or home-state-only sellers, manual compliance may still work.
Sources
- SMAART Company. Small Business Multi-State Sales Tax Frameworks, 2026.
- South Dakota v. Wayfair, Inc., 138 S. Ct. 2080 (2018).
- Federation of Tax Administrators. State Sales Tax Rates, 2025. taxadmin.org
- American Institute of Certified Public Accountants. Post-Wayfair Sales Tax Guide, 2025. aicpa.org
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