I have a Brit passport, with a non immigrant O visa that will expire the first week of April.

I can not put 400.000 Baht into my bank account to meet the 60 day requirement and obtain a marriage visa before this visa expires, I have more enough money in a joint account with my wife, and I can transfer any amount of money into my own account in 24 hours.

I would like to extend my present visa for at least 60 days.

So what are my best options, can I get an extension of 60 days in BKK, if I must leave Thailand where would the best place to go to obtain multiple entry one year Non O visa

If you wanted to you can get a 60 day extension to visit your Wife from Immigration. Just take the Marriage Certificate and Wife's ID Card and House Book.

Once your 400,000 has been in your bank for 60 days you can apply for the 12 months annual extension. It is not a visa.

Agree with Lite Beer.

But you won't get the extension in Bangkok if you don't live there. You have to go to the assigned office for where you live.

Also you say that your visa is expiring remember if it is a multiple entry visa that you can make one more border run and get another 90 day entry as long as you do it before the experation date.