Do I need to open a local bank account and season the funds before applying for a one-year extension on my Non O retirement visa?

I'm shutting this down. This is NOT a banking advice group or a money transfer advice group. I think the OP got the answer he need. TALK to the local immigration office about the time frame needed to get a one year extension of stay based on retirement. ASK about banking in a local Facebook group where you will live.

IF you want commenting reopen, please send a mod a message. Thank you.

totally agree with TOD arriving here on Phuket on Friday the 1 you have to wait till Monday morning to open a bank account on your name .. I advise to try the Kasikorn Bank witch is normally easy to handle . The only thing they need is the. Address you are living .. Do you have a condo or renting contract? If not tell them the Adress of your hotel . Ask the hotel to give you a letter that you stay there .. it will help

you got your wires crossed a bit

That 14 days before your stamp runs out is to APPLY for an in country 90 day Non-O visa, you are saying you will enter the country on one you get from the thai consulate in your country before you come here

So that means if you enter the country on a 90 day Non-O visa on Oct 1st you'll get stamped in for 89 days (the day you arrive counts as day one) so until about Dec 29th. <- that's the date your ENTRY STAMP will expire (nothing to do with the visa at all, it will be marked USED when you enter and that's it for it). 😉

In Phuket you can apply for a yearly extension when you have 45 days or less left on your current stamp <- meaning the earliest you could apply (if you met the seasoning requirements) would be about Nov 15th

The thing that totally controls when you can apply for your first yearly extension is having your funds in a thai bank account in your name only seasoned the 2 months before you apply.

My advice, get the bank account open as SOON as you hit the ground here and get the funds transferred into the account.

The sooner you do that the sooner you can season the funds for 2 months and then apply for your year extension before your 90 day stamp runs out (because there is no other extension available to you on a Non-O based on retirement except the year one).