The listed price for ChatGPT Plus is $20 per month, but the actual charge can...

https://smoothdecorator.com/why-did-openai-keep-chatgpt-plus-at-20-since-february-2023/

The listed price for ChatGPT Plus is $20 per month, but the actual charge can vary between $13 and $27 depending on where you subscribe. This happens because of extra fees like VAT or GST in some countries, or app store markups on iOS and Android