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

https://source-wiki.win/index.php/How_Early_Should_I_Cancel_ChatGPT_Plus_to_Avoid_Being_Charged%3F

ChatGPT Plus is listed at $20 per month, but the actual price you pay can range from about $13 to $27. This happens because taxes like VAT or GST and fees from app stores get added on top