I believe what they want to see is that you have a revenue stream outside of Thailand. For example, you can show that you are a consultant in different industries, either creative or technical, but you would want to demonstrate that you’re making money doing those things. What I did was show a proposal I sent to a client, screenshots of the work completed, and screenshots of the deposit showing the client paid for the work. If you have a children’s book, you’d want show how you’re making money from it, or make a case for how it contributes to your income.
that’s great! For financial proof I just included one bank statement for the latest month showing the amount required. Did you include anything more than that, or tax forms, or anything along those lines?