@Carsten *********
:/
You would have to check with Jomtien, BUT you can't use quarterly deposits into a thai bank to hit the proof of funds for monthly income.
The rule is totally clear, a minimum of 65K baht per month each month EVERY month for the preceding 12 months before you apply for the extension.
I believe you cannot use monthly income as a method to meet the proof of funds and would have to use the 800K baht banked money method.
You need to check with Jomtien BEFORE you need your extension to see what they will and won't accept