ChatGPT Plus is listed at $20, but the actual price you pay can range from $13...

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

ChatGPT Plus is listed at $20, but the actual price you pay can range from $13 to $27. This difference is mainly due to taxes like VAT or GST and fees added by app stores, especially on iOS and Android