TaxLocus watches your Shopify orders and tracks economic nexus — the sales thresholds that, once crossed, require you to register for and collect sales tax in a US state. Every order shipped to a US address is attributed to its destination state and added to a rolling 12-month total, then compared to that state's current threshold. See at a glance where you're clear, approaching, or have crossed one and need to register. All 50 states and DC, kept current. Not tax or legal advice.