What paperwork do I need for a visa extension in Thailand for my stay from mid-July to mid-September?

To extend your stay in Thailand from mid-July to mid-September, you'll need to be aware of your entry status: if you're entering with a tourist visa or visa-exempt. If you have a tourist visa, you'll be stamped in for 60 days or more; if visa-exempt, you'll initially receive 30 days. To extend your visa, you generally need your passport, two passport-size photos, and 1,900 THB. It's also important to ensure that your accommodation is properly registered (TM30) before application at the immigration office.