Presently using my US passport for my non immigrant O visa for retirement and would like to change it to my British Passport. Will be returning to Thailand in 9 days. Do I need to show an onward ticket? Will be entering with British passport previous entries have been with US passport. Any suggestions?

Your post is not clear. Do you have a new non immigrant O visa in your UK passport? You can not show a visa in a US passport and use that for entry on another country passport if that is what you are asking. So if you plan to entry without a visa you will likely be required to show an onward ticket by airline unless you check-in using a passport with a valid visa in it.

If you have a visa you do not need to have an return or onward ticket.

Since you are using passports from different countries you will have to use the passport with the visa when you enter the country.

Your post is not clear. Do you have a new non immigrant O visa in your UK passport? You can not show a visa in a US passport and use that for entry on another country passport if that is what you are asking. So if you plan to entry without a visa you will likely be required to show an onward ticket by airline unless you check-in using a passport with a valid visa in it.

I currently have a non immigrant O for retirement in my US passport that expires in January. I would like to replace that with my UK passport.

I have to leave the US on my US passport and it still has the valid non immigrant O. When I go through immigration in Bangkok I would like to use my UK passport and receive the 30 visa exempt stamp. I would then be able to open a new bank account with my UK passport and wire in the required 800000baht. I would then follow the required steps to convert to the non immigrant O for retirement. My main question is--can I pass through Thai immigration without an onward ticket??? Does anyone see any problems doing this conversion?

Immigration will not care or look for onward ticket. Should not be any problem.

The airline will ask to see an onward or return ticket. If you still have a passport with a valid visa you could use it to show to the airline. Immigration does not ask for your tickets.

Edit: Remember you are going to have a limited amount of time (about 2 weeks) to get the bank account opened and money in the bank before going to immigration.

Also be sure you get a letter from bank confirming your bank balance before going to immigration.

Edited October 6, 201213 yr by ubonjoe

Immigration will not care or look for onward ticket. Should not be any problem.

Thanks a lot Lopburi that saves me some $$ and a trip I didn't want to take. Your expertise in these matters is appreciated.

The airline will ask to see an onward or return ticket. If you still have a passport with a valid visa you could use it to show to the airline. Immigration does not ask for your tickets.

Thanks ubonjoe.