ChatGPT Plus lists for $20 a month, but the final price you pay changes...

https://www.primary-bookmarks.win/chatgpt-plus-has-a-20-list-price-but-the-actual-cost-you-pay-can-range-from

ChatGPT Plus lists for $20 a month, but the final price you pay changes depending on your country and device. Taxes like VAT or GST get added, and if you buy through an app store, they tack on their own fee too