ChatGPT Plus has a list price of $20 per month, but the actual cost can vary...

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

ChatGPT Plus has a list price of $20 per month, but the actual cost can vary between $13 and $27 depending on where you buy it. This happens because of factors like VAT or GST taxes and extra fees from app stores like Apple or Google