Note: my experience below involves a person on a retirement extension based on a supporting Thai bank deposit:
Just an UPDATE from BKK CW today, re the process of transferring one's extension stamps into a new passport, and it was a SHOCKER!
In addition to the list of required photocopies I posted in the prior post, all of which Immigration indeed wanted today, they also wanted to:
1] inspect my original Thai bankbook holding my 800K retirement extension deposit to make sure my balance hadn't dropped below the required levels;
2] have me do a print balance update of that bankbook today as part of my application, and
3] provide them with signed photocopies of all the bankbook pages covering the entire 1 year period of my current extension.
None of that pertaining to the bank info is listed anywhere on Immigration's own documents checklist (posted above) for getting stamps transferred into a new passport. So I checked with the officer handling my application, and she confirmed it, and I later spoke with her supervisor there in English, who also confirmed it.
I couldn't quite get them to clarify if this was an old or new rule... But the supervisor told me, nowdays, if you are doing any business at BKK CW's L section where they handle retirement extensions, and your retirement extension is based on a Thai bank deposit, they're going to ask you for all three of the bank-related things above.
I asked them further, and they clarified that the bankbook update and related photocopies stuff will NOT apply if an extension holder based on a Thai bank deposit is going to BKK CW to do business at the 90-day report section or the re-entry permit section or any other sections. But if you're doing any business at the L extensions section, they said they will require you to produce the bank stuff.
Yesterday, in preparing for today's visit to BKK CW to get my stamps transferred to my new passport, I read a half dozen or so related threads on that general topic here on the forum, and I think there was only one poster (SooKee) who mentioned BKK CW requiring the bankbook update and photocopies as part of the transferring stamps to a new passport process.
My guess last night was that he was probably wrong about that, since pretty much nobody else had mentioned it in their various posts. But I figured I'd bring along my Thai bankbook holding my retirement extension deposit just in case. And I'm glad I did, because he was 100% correct about that. And if I hadn't brought my bankbook, it would have been a wasted trip and day out to BKK CW.
Two other detail issues that have gotten discussion in these threads:
1. As least for me as of today at BKK CW, there was NO FEE charged for transferring my Immigration stamps from my old passport to my new one.
2. And other than the bank info subject I've explained above, Immigration's documents checklist that I posted above is correct. They only wanted the photocopies of the most recent stamps for current extension, most recent entry, most recent visa, etc. -- and NOT photocopies of every used page from my old passport, which would have been a LOT of photocopies.
Hope the above is helpful and useful.