ChatGPT Plus is listed at $20 a month, but the actual price you pay can vary...

https://highstylife.com/i-keep-hitting-chatgpt-limits-should-i-start-a-new-thread/

ChatGPT Plus is listed at $20 a month, but the actual price you pay can vary from about $13 to $27. This difference comes from added taxes like VAT or GST and extra fees from app stores like Apple or Google