Mario De Mey If you deposit a minimum of THB
*****
.- each month in a Thai Bank account you need to do that for at least 12 months before you can apply using this Method. So not possible for the first Year after getting your Thai Bank account.
You can maybe get a Letter from your Belgian Embassy confirming your Pension payments in Belgium. Since you started Retirement last year in May only you cannot do this right now.
So if you can transfer THB
*****
0.- into your new Thai Bank account then this will be the easiest way for this first Year. After the Money is in your Thai Bank Account you have to wait at least 2 Months before it will be accepted by Immigration.