[AI-Native Tax Engine Company Sphere Secures $21 Million Series A Funding Led by a16z] AI-native tax engine startup Sphere announced the completion of a $21 million Series A funding round, led by a16z, with participation from Y Combinator, Felicis, 20VC, and others. Sphere leverages AI to automatically interpret global tax laws and enables end-to-end tax compliance automation required for global expansion through more than 100 local tax filing channels. Dubbed the 'tax version of Deel,' the system is specifically designed for cross-border revenue compliance, aiming to allow businesses to 'operate globally' from day one.