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

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

ChatGPT Plus is listed at $20 a month, but the actual price you pay can vary between $13 and $27 depending on where you sign up. Differences in taxes like VAT or GST and app store fees can change the final cost