What are the requirements for the 800k THB deposit when applying for a non-O retirement visa extension in Thailand?

You may not be able to open a Bankaccount, until you have a proper adress in Thailand, and have stayed at least 3 month on a longterm visa.

Banks in Thailand are like everywhere in the world, interested in having good stable custormers, that have a permanent address, a steady easy traceable income, and use the account all year round.

That is why the banks are reluctant to give accounts to people on short time ( read: tourist ) visas, and who only spend part of the year in Thailand.

Don’t expect to get a residence certificat, until you have stayed at a permanent adress in at least 3 month, since that is what the residence certificat should confirm.

Furthermore the added attention on whitewashing of money, is an added burden on the banks, so even depositing large amounts isn’t a guaranteed way to open an account.

The value of a resident certificat, had gone down, since Immigration Officers are giving them to people that are not on a longterm visa, or have stayed severel months at 1 adress in Thailand, so even if it is a formal requirement, the bank make up their own assesment of the stability of the want-to-be customer.

No need to worry about international transfer at all. Although I certainly wouldn't recommend bringing that amount in cash or by cheque, you have to declare anything over 20k USD to customs. Better just to transfer. I think every immigration office requires the funds are seasoned for 2 months for the 1st 12 month extension. Some require 3 months for subsequent extensions

1) You only have to prove the funds in your name in a thai bank account. Only the initial 90 days Non O requires proof of international transfer.

2) The funds need to be seasoned for two -not three- months before you apply for the extension of stay. (Three months after the extension is issued). So you’ve got one month to set up a bank account with the required funds.