Tax Calculation/Compliance。Stripe Tax (内蔵・$0.50/Transaction)・Avalara AvaTax (Enterprise最大手)・TaxJar (Stripe子会社)・Anrok (SaaS特化)・Quaderno (Indie SaaS最適)・Octobat (旧Quaderno競合)・Vertex (Enterprise)・Sovos・Lemon Squeezy内蔵・Paddle MoR内蔵 (Tax代行)・Sales Tax/VAT/GST・Reverse Charge・¥¥¥¥¥-¥¥¥¥¥¥¥/月、2026年MoR (Paddle/LemonSqueezy)で税務代行主流化。