Sales Tax Nexus After Wayfair: 2026 Compliance Guide

The 2018 South Dakota v. Wayfair decision rewrote sales tax for every U.S. seller. Eight years in, most SMBs still get it wrong - usually by registering in too many states too early, or by ignoring nexus until a state finds them. Here is the 2026 playbook from our sales tax practice.

What economic nexus actually means

A state can require you to collect sales tax once you cross its economic-nexus threshold - typically $100,000 in sales OR 200 transactions into that state in the prior 12 months. About a third of states have dropped the 200-transaction trigger; most now use a pure dollar threshold.

Physical nexus still wins

Inventory in an Amazon FBA warehouse, a remote employee, or a single trade show can create nexus instantly - no dollar threshold required. This is where the largest unpaid-tax exposures hide.

The correct registration order

Do not register state-by-state in alphabetical order. Run a nexus study first.

• Pull 12 months of orders by state.
• Identify states where you have crossed the economic threshold.
• Identify states with physical nexus (FBA inventory, employees, contractors over thresholds).
• Register, then back-file only where lookback exposure is material - many states offer voluntary disclosure agreements (VDAs) that cap lookback.

Marketplace facilitator rules

Amazon, Etsy, Walmart, eBay, and most major marketplaces now collect and remit sales tax on your behalf in every state. But you may still need to register and file zero returns to stay compliant - and your direct (Shopify, WooCommerce) sales remain yours to handle.

Get a one-page exposure map

Send us a CSV of 12 months of orders and we'll return a state-by-state nexus map and a prioritized registration sequence. See the sales tax service or book a call.