I do my immigration business at Jomtien, and from memory they wanted a 12 month statement first time about 4 “O”visa extensions ago. I thought at the time it was because I’d changed the passbook due to the one I had at the previous renewal being full. As a precaution though I now always get one with my letter required from the bank. IO seem happy with that. For Thb 100 it’s not worth having the dialogue with immigration, so I just include it with the passbook photocopies they want.