How long does the 400,000 Baht need to be in the bank to renew a Type O Thai Wife visa?

Chaengwattna allows you to apply for your 1-year extension when you have 45 days or less remaining.

This is the general information for a 1-year extension based on married to a Thai, you need to get the latest requirement from CW.

the 400K baht banked money method for a year extension based on marriage to a thai national needs to be seasoned 2 months BEFORE you apply <- not before your current stamp runs out. SO it all depends on when you apply.

At most offices you can apply 30 days before your stamp runs out so you could apply any time after Dec 31st.

Make sure what ever day you're going to apply for your next year extension that the money is seasoned in a thai bank account in your name only for 2 months before that