Do I need proof of onward travel within 60 days if I plan to extend my tourist visa in Thailand?

When flying into DMK on a tourist visa, it's necessary to present proof of onward travel. Typically, this should be within 60 days of your arrival. However, if you plan to apply for a 30-day extension of your tourist visa, you may argue that your proof can extend to within 90 days, depending on your travel itinerary and the discretion of the immigration officer.