Navigating the Maze: A Founder’s Guide to eCommerce Sales Tax
Disclaimer: Inverse Paradox provides eCommerce consulting and is not a Certified Public Accountant (CPA). The following information is for educational purposes only. For specific tax advice and compliance, please always consult with a qualified tax professional.
One of the most daunting aspects of running an online store isn’t sourcing products or designing the website—it’s handling sales tax. It is the invisible friction that keeps many founders up at night.
If you are confused, you aren’t alone. The landscape of digital sales tax has shifted dramatically in the last few years. The good news? Your eCommerce platform is likely doing the heavy lifting for you—but only if it is configured correctly.
Here is a breakdown of how sales tax works for modern online retailers, why “Nexus” matters, and why your product categorization is more important than you think.
The “Physical Presence” Rule
Historically, you were only required to collect sales tax in states where you had a “physical presence.” This is often referred to as Physical Nexus.
If you have a brick-and-mortar shop, a warehouse, a remote employee, or even inventory stored in a third-party fulfillment center in a specific state, you likely have physical nexus there. In these states, you are legally required to register and collect sales tax on orders shipped to customers within that state.
For most small businesses starting out, this means you only collect taxes in your home state.
The New Reality: Economic Nexus
Here is where it gets complicated. In 2018, the Supreme Court ruled in South Dakota v. Wayfair, Inc. that states could require remote sellers to collect tax even without a physical presence, provided they meet certain “economic” thresholds.
This concept is called Economic Nexus.
States realized that if every small website selling a $5.00 item had to register and file taxes, the administrative cost for the state would outweigh the tax revenue collected. To solve this, they established thresholds. You generally only have to register and collect tax in a new state if you surpass their specific annual revenue or transaction count limits.
The thresholds vary wildly by state:
- California: Generally requires registration if you surpass $500,000 in gross sales into the state.
- South Dakota: Requires registration if you surpass $100,000 in gross sales.
Modern eCommerce platforms (like BigCommerce, WooCommerce, or Shopify) have built-in “tax monitors” that attempt to track your sales against these thresholds. They will often alert you if you are approaching a limit in a specific state, recommending that you register. However, these platforms cannot enforce the law or file for you, that is where your accountant comes in.
Destination-Based Tax
Once you have established that you do need to collect tax in a specific state (either due to physical presence or economic nexus), the rate you charge is almost always based on the Shipping Address of the customer.
If you are based in Pennsylvania and ship to a customer in California (and you haven’t hit California’s $500k threshold), you generally do not charge that customer sales tax. If you ship to a neighbor in Pennsylvania, you do.
Note: This is evolving rapidly. Digital goods, software, and non-deliverable services are increasingly being pulled into these tax nets, so keep an eye on your specific industry regulations.
The “Fun” Nuance: Product Categorization
Setting up your nexus is only half the battle. You also have to ensure your products are tagged correctly in your system.
Why? Because not all products are taxed equally. States have complex taxonomies regarding what is considered a “necessity” versus a “luxury.”
The “Formal Wear” Example: Here in Pennsylvania, home of Inverse Paradox, everyday clothing is generally tax-exempt; you don’t pay the standard sales tax on a t-shirt. However, the state distinguishes “formal wear” as a luxury.
- Everyday Dress: Tax-Exempt ($0.00 tax).
- Formal Gown: Taxable (Standard Sales Tax Rate).
If your online store treats every product as a generic “physical good,” you might be over-collecting tax (upsetting customers) or under-collecting tax (upsetting the state).
What You Should Do Now
- Review Your Store Configuration: Go into your platform’s settings and verify that every physical location where you hold inventory or have staff is listed and tax collection configurations are accurate. This ensures your “physical nexus” baseline is accurate. If you believe you already have economic nexus in other states for which you are not collecting, consult with your accountant immediately.
- Audit Your “Taxable” Flags: Ensure your products are set to “taxable” by default, unless they are specific exempt items like Gift Cards (which are taxed when redeemed, not when purchased).
- Categorize Your Products: Don’t just list items; assign them to the correct product tax categories in your platform’s backend (e.g., Apparel & Accessories > Clothing vs. Sporting Goods). This allows the automated tax engines to apply the correct state-specific exemptions.
- Watch Your Thresholds: Keep an eye on your platform’s tax settings for alerts regarding Economic Nexus in states where your sales are growing.