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

https://www.slideserve.com/aaron_ward92/why-does-chatgpt-plus-cost-more-on-android-than-on-the-web

ChatGPT Plus is listed at $20 per month, but the actual price you pay can vary between $13 and $27 depending on your location and payment method. This happens because taxes like VAT or GST and app store fees get added on top