Can I extend my TR visa for 30 days and how does it affect my stay duration?

You can extend your TR visa by 30 days, which will be added to your existing entry stamp, resulting in a total of 90 days from your original date of entry. For the extension, aside from your passport, departure card, and the 1,900 Baht fee, you will also need copies of your passport data page, entry stamp, a filled-out TM7 form, and a passport photo.