What are the requirements for transferring funds and applying for a retirement visa in Thailand?

Okay, here's how this works

To apply for the INITIAL 90 day Non-O visa based on retirement at the immigration office at Chaengwattana in Bangkok using the 800K baht banked money method you DO need to show that the funds originated from overseas. Period, end of story. Your immigration office might not require it BUT Bangkok does.

Now with that being said once you have the 90 day Non-O visa to apply for a yearly extension of stay based on retirement using banked money method there is NO requirement that you show where the funds came from (it can be a domestic transfer/deposit). The ONLY requirement is that the funds are in a thai bank account in your name only for 2 months before you apply for the yearly extension.

And to answer your other question, you can bring in the funds in multiple transfers if you want as long as you can prove they all came from abroad AND they total more than the 800K baht

>Does it need to show it was an international transfer?

Yes it does

> My Krungsuri bank statement shows a transaction code of TN

You'd have to ask them.

>Second question is how long does it need to season before I can apply for the applicable VISA?

There is no seasoning requirements for an in-country Non-O visa. There is a seasoning requirement for a one year extension of stay based on retirement. The money must be seasoned in a bank account for TWO months.