Sales Tax Nexus Analyzer

Produce a defensible multistate sales-tax nexus study and registration plan for a remote seller, SaaS company, marketplace seller, or hybrid retailer. The skill takes a sales-by-state revenue and transaction-count profile, overlays the **state-by-state economic-nexus thresholds** captured in `knowledge-base/regulations/sales-tax-nexus-thresholds.md`, layers in **physical-nexus** factors (employees, inventory in 3PL warehouses, contractors, trade-show attendance), and produces a six-section deliverable: (1) executive summary, (2) state-by-state nexus schedule, (3) physical-nexus exposure summary, (4) Voluntary Disclosure Agreement (VDA) candidate list with back-tax exposure ranges, (5) registration and collection plan with go-live dates, and (6) ongoing compliance calendar. Built post-*South Dakota v. Wayfair, Inc.*, 585 U.S. 162 (2018), and reflects the post-2024 trend of states repealing transaction-count tests in favor of dollar-only thresholds. Designed for CPAs, EAs, state-and-local-tax (SALT) specialists, and CAS / advisory practitioners.