I opened term deposit with Bangkok Bank by transferring money from my savings account. I did get a separate bank book. Actually I opened 2 X 12 months term deposits - one 820k, the other 250k. As far as I know, there are no issues with the Samui immigration if you have 2 bank books, they are both with the same bank and there is clear trail. Anyway I don't need it now, currently in the country on visa exemption, departing again next month. If I do move to non-O retirement again it would be much simpler way to maintain. No tens of transactions in the bank book, and term deposits are generally safer, difficult to scam them, no ATM card attached to them.