First--For the letter from the bank (Bangkok Bank) for marriage extension. Do I have to get the letter from the branch I started the account or will any branch do.

Second- for getting an extension to an nonim O multi ( non marriage ). Do I need to get it before the "use by" date or the end of the last 90 day stamp?

I think that it's best to go to your own branch. Staff are expert in finding excuses to refuse a transaction with which they aren't familiar.

Make sure that the photocopy your bank book and do not print a statement from their own printer. My local visa office rejected a printout.

The date for expiry is the one, not the 90 day stamp date.

You should be able to get it at any branch but some will tell you no. A mini branch like those at Tesco would not be a good choice.

You can do your extension during the last 30 days of any 90 day entry from your visa.

Edit: You do not have to wait until your visa expires ( edited to correct incorrect info in post #2).

During the last 30 days of the permitted to stay stamp. Visa can already have expired and visa date has no meaning. You can use letter for any bank branch but good luck getting it. Unless from the branch at Chiang Watanna; manager is not likely to issue a letter for an account in another branch from all reports we have seen here - but they might be able to obtain from hqs for you.

During the last 30 days of the permitted to stay stamp. Visa can already have expired and visa date has no meaning. You can use letter for any bank branch but good luck getting it. Unless from the branch at Chiang Watanna; manager is not likely to issue a letter for an account in another branch from all reports we have seen here - but they might be able to obtain from hqs for you.

Good point. Go early. They don't like to process applications for annual extensions close to the final day. Aim for 30 days in advance.

The bank should have a standard letter to use. Inexperienced clerks may not know abut it and try to get you out of the door. You must persist.