ChatGPT Plus is listed at $20 per month, but the actual price can vary between...

https://wiki-global.win/index.php/Why_Does_ChatGPT_Plus_Cost_More_Than_$20_for_Me%3F

ChatGPT Plus is listed at $20 per month, but the actual price can vary between about $13 and $27 depending on your location and platform. The main reason is extra taxes like VAT or GST, and app stores like Apple and Google add their own fees