Indeed. But an actual statement (Thai) will show it as a foreign transaction. Never been an issue for me, of course there is nothing predictable about the behaviour of individual immigration offices(or officers).
Get the standard letter and a 12 month statement. These can be done several days ahead of time. But on the day you apply for the extension make some transaction in your account (in or out) and update the bank book.
I have been sending from Wise to Kasikorn for a long time. Irrespective of then reason given for transfer the bank book always shows TRN. The statement however always shows "รับเงินธุรกรรม ตปท" which Google tells me means "Receive money from overseas transactions". I never had any issues with that.
Final note, as you may have read Wise has restricted the banks it will/can send to. Although Krungsri is listed on their list of possible banks there is another thread running on here where people are getting transfers rejected to banks on that list. I would highly recommend you make a trial transfer as soon as possible to ensure that you can actually use Wise if you choose to do so for the extension money.
Actually just checked the app which now says other banks are 500,000.
Recipient bank
Maximum per transfer (THB)
Bangkok Bank Public Company
2,000,000
Kasikorn Bank
2,000,000
Siam Commercial Bank
1,499,999
Other recipient banks
500,000
When I did my first extension last year all my transfers to my account were done using Wise from the UK. I always selected "funds for long term stay" as the reason for the transfer but at least for my bank, Kasikorn, it makes no difference to how they show on the statement, all transfers, irrespective of reason, show up as international (I'm not entirely sure that's even important).
Nope, he didn't need to check your code because he can see on his system that you've done it. If you hadn't you'd have been sent away to get it done. Random codes will not work.