Will my boyfriend's father face issues extending his retirement visa in Bangkok after receiving it in Trang with an agent's help?

Yes, they will likely extend it. But only know for sure once you go to immigration

Why don't you ask the agent?

Changing location not issue.

My 1st was bkk, next year Chiangmai, then Chonburi 1 year, back to CM many years. all on income, but income must show from abroad.

IO will want Bankbook showing FTT, for 12 months. Letter from Bank.

I had no problems changing from an agent to getting my stamp at my local office once I had managed to meet all the criteria. The only thing my local office would not do is transfer my stamp to my new passport. They did not check that I had met the financial requirements for the previous year. I used a different bank account with the banked money which showed it had been there for three months prior to application. That was good enough. I'm not saying that this would be the case at every office.

I live in bangkok and 3 years ago when I moved from Pattaya to Bangkok I used a well known agent in Bangkok to do the changes for my visa as at the time I was unwell. The visa was issued in Trang even though my property was registered in Bangkok. I had the money in the bank and gave the agent all the statements etc when she renewed my visa. When I went to renew it myself last year in person in Bangkok the visa was declined due to me using an agent in the past. I had to go back to the agent and pay the agency fee to renew my visa. Be warned hopefully it will not happen to you

His problem is going to be with the fact he used an agent and that agent supplied the money for the extension he's currently on. You also imply there was a week after he got the extension where the 800k baht wasn't in his bank account. There are a number of potential issues here

1. He did not honour the terms of the extension he's currently on regarding money so will be unlikely to get a new extension

2. Depending on just how the agent obtained the visa and extension other immigration offices may not want to touch it

There's 2 options as I see it

1. Go back and use the same agent again

2. Go out of Thailand without a re-entry permit to cancel his current extension. Come back on a tourist stamp and start over with a 90 day non-o visa then a 12 month extension but doing it himself without an agent

The problem with using agents is you can be stuck using them for ever

The only problem that I can see is immigrations may want to see the original bank account to verify the account never fell below THB 400,000.

Make sure that 65k Baht is being deposited as an international wire transfer, I don't think deposting locally is acceptable. To prevent money laundering, I believe that the wire transfer has to indicate some sort of institution, retirerment fund, etc. At least what institution or organization it's coming from.

If he is properly registered in that province he will be fine.

My first extension was issued in Ubon. My second in BKK and every one after in Jomtien.

I should add if all other requirements are met. Changing locations is not an issue

In order to switch over he will need bank statements from every month last year showing that the bt800,000 was in his account for at least 3 months after he got his extension, and then that the balance never dropped below bt400,000 for the rest of the year. Without bank statements showing this they will not extend his extension, as he won't be able to prove be met the requirements for the last year. This is the main problem with using an agent when you never had the bt800,000.

Maybe you never know if his tm30 is from Bangkok it should help but people have had problems switching from an agent to doing it yourself