ChatGPT Plus has a listed price of $20 per month, but the actual cost you pay...

https://ericksexcellentblog.image-perth.org/chatgpt-plus-message-limit-is-it-really-160-messages-per-3-hours

ChatGPT Plus has a listed price of $20 per month, but the actual cost you pay can vary from about $13 to $27. This difference comes from factors like local taxes (such as VAT or GST) and extra fees added by app stores on iOS and Android