Its all based on the person you meet at the individual bank branch. Every branch and sometimes individuals have different requirements. Like most formal stuff in Thailand 🤷🏻♂️
I opened my accounts at first attempt based on Medical treatment + DTV. All they wanted to see was my Visa and ongoing medical treatment. This was in Bangkok just a few months ago.
But what is important: Dress formal when going to the bank. Bank employees are considered «authority», and in Thai culture presenting yourself formally when dealing with bank, immigration, or any authority does matter.
Showing up in flip flops, shorts and singlet is a sure wat to get rejected.
first has to be done in person or by post. In Bangkok it easily takes the better part of a day as immigration is way out. 300b for the saved time, way worth it….