Two products, two bills
ChatGPT (Free, Plus, Pro, Team, Enterprise) is the chat product billed as a subscription or consumer usage. OpenAI API credits are prepaid Platform balance for keys used in code. They do not share a wallet. If you can chat at chatgpt.com, you still need a Platform account to call the API.
Official prepaid billing: OpenAI prepaid billing guide. Last verified: 2026-08-18.