Do I Need a Thai Bank Account for Visa Financial Requirements?

Are you asking about meeting the proof of funds to buy a VISA from a thai consulate in another country OR asking about meeting the proof of funds to get a yearly extension of stay inside the country at the immigration office?

What are you talking about?

To meet the financial requirements for a yearly extension of stay you either bank the required amount of money in a thai bank account for the seasoning period before you apply for your extension

OR

Depending on your nationality you get a letter from your embassy here stating you get the required monthly income in your country.

OR

If your embassy doesn't issue the affidavit of income from abroad notary letter, you transfer IN to the country each month every month for the preceding 12 months the required money into your thai bank account.