If you get a pension and you have not paid any tax on your pension in the 2024 financial year in your home country, you are liable for that tax in Thailand if you live here for more than 180 days. There are quite a few credits that you can claim. This incudes expats here that we know that has been to the Tax office Astralian and Canadian that have to pay tax here.
Everyone will get it eventually. All the banks are trying to get rid of the "mule" accounts. We are not the only ones to get the notification from the bank to go and verify our accounts, quite a few already that we know of.
If you want to retain your Thai bank account. You need ro provide this information. You are also required to provide your Thai TIN number if you have that already.