I have a fix saving account and my wife told me that the bank will deduct tax on the interest I earn from the account. Can I file a return to get this interest back, since I am on a retirement visa and have no other income in Thailand. I read something about a tax number also, do I need that and how to obtain. Any help on this subject would be appreciated.

Ok so what time do the tax accountants come to work?

Sure you can get a refund...you can file for it from 1 Jan-31 March of each year...it not hard to get the refund at all. Been several threads on the subject. For example, here's a thread I started to describe my personal experience this year to file and get a refund on the 15% withholding tax applied to my fixed saving account. Link

Thank you Pib. Very helpful.