ChatGPT Plus is listed at $20 per month, but you might pay between $13 and $27...

https://station-wiki.win/index.php/Why_Do_My_Answers_Get_Worse_After_I_Hit_a_Limit_on_ChatGPT_Plus%3F

ChatGPT Plus is listed at $20 per month, but you might pay between $13 and $27 depending on where you subscribe. Differences come from taxes like VAT or GST and fees added by app stores such as Apple or Google