ChatGPT Plus is listed at $20 per month, but the actual price you pay often...

https://smoothdecorator.com/why-did-openai-keep-chatgpt-plus-at-20-since-february-2023/

ChatGPT Plus is listed at $20 per month, but the actual price you pay often varies between $13 and $27. This difference comes from extra taxes like VAT or GST and the fees added by app stores on iOS and Android