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

https://mike-wiki.win/index.php/Is_There_a_ChatGPT_Plus_Free_Trial_I_Can_Click_to_Start%3F

ChatGPT Plus is listed at $20 monthly, but the actual price you pay can vary between $13 and $27. Differences come from taxes like VAT or GST and extra fees from app stores on iOS and Android