When is the best time to apply for a one-year extension based on marriage to a Thai spouse before the current visa expires?

What I would advise you do

@Cr***

is;

a month or so before you're going to apply for your new yearly extension, go to the immigration office with your thai wife. Get the hand out listing the requirements AND while you're at it have her ask if there is anything required that is not on the handout.

That way you will know for sure what's required..

Good luck with it, take care, stay safe (y)

At MOST immigration offices you can apply for a new yearly extension when you have 30 days or less left on your current stamp SO you could apply middle of June 2021.

You need the photos, the documents, the copies, the bank letters, the bank book updated etc exactly like you did before.

When you apply (just like last year) you will get a 30 day under consideration stamp (some offices will do an in home visit) and then when that 30 day stamp is up you go back to get the year extension inked in

Why would you be marked down as a overstayer IF you're getting a new extension BEFORE your current stamp expires <- dial the paranoia back just a notch or three ;)