Sphere, the AI-driven tax compliance platform founded by Nicholas Rudder, has closed a $21 million Series A round led by a16z, with participation from YC and Felicis Ventures. The San Francisco‑based startup automates global tax registration, calculation, filing, and remittance for companies expanding internationally. Integrations with major billing systems like Stripe enable real‑time tax assessment, while its proprietary AI engine, TRAM, codifies jurisdictional rules and provides citation‑backed determinations. Sphere aims to extend its infrastructure to more tax authorities, grow its engineering and sales teams, and become the essential tool for finance teams navigating cross‑border compliance. Read more →