I am about to finish up my first year in Thailand under a Non-Immigrant "O" Visa based on marriage. My assumption has been that I will need to leave Thailand and apply for another Non-Immigrant "O" Visa from scratch. I plan to do this in the United States, but I also am aware that I can make the application in any country other than Thailand.

I have heard, however, that I could also make the application for a second Non-Immigrant "O" Visa from within Thailand. Is that possible and how does that work?

You can within Thailand apply for a EXTENSION OF STAY BASED ON MARRIAGE with your valid Non immigrant O in the bottom, But you must do this before your Non O expires....

You will have better answer from the pro´s here in this forum... but this is Ok to do in your case.

Glegolo

You need a lot of documents as well.

Someone will be along soon and provide you with a detailed list, but in the mean time here is what I use

TM7 Application x 2

Passport + copies

TM6 + copies

Yellow Book + copies

Embassy Income letter + copies

Bank Books + copies

Marriage Certificate + copies

Registration in Amphur + copies

Affirmation to Marry + copies

Map to Condo + copies

Pictures + copies

Wife's ID Card + copies

Wife's Blue book + copies

Wife (original only)

For the application you must have an income of 40,000baht per month, if from within Thailand you will need pay slips, if your income is from outside of Thailand then you need a letter confirming this from your Embassy.

The above is one way, the other is if you have an account with over 400,000baht in it, and it must by your account and not a joint one.

If using the bank deposit financial method for "Thai wife" extension of stay it must have been in account for the previous two months at time of application.

With extensions of stay you no longer have to leave the country every 90 days for a new entry as it will be for one year and the same process each year. But you will have to report your address (or have someone do) to immigration every 90 days you remain in Thailand without leaving.

As you appear to be over age 50 you have another option available with a lot less paperwork if you can meet the financials of 65k per month into or 800k in bank account here 2 months or a combination to meet 800k per year. This you do yourself and only the financials and some form of residence document are normally required. This is obtained immediately so easier for most. You start the same with TM.7 form during last 30 days or a 90 day non immigrant O visa entry.

Thanks to all of you who responded. My time is short, so cannot really change what I've set-up, but I will use this info on the next trip to hopefully save me some hassle.