I have been married to a Thai woman for 3 years and usually come into Thailand on a Non-Immigrant O multiple entry one-year visa that I have gotten at Thai Consulate in Honolulu. I had problems with scheduling in Honolulu this time and entered Thailand on standard Tourist on Arrival 30 day Visa. I am planning to stay at least 6 months and want to change Tourist Visa status to Non-Immigrant O. Does anyone know if this can be done at Thai Immigration Office (I am in Chiang Rai so Mae Sai office is closest)?

The only way such an entry could be changed would be for a one year extension of stay to live in Thailand with proof of 400k in Thai bank account or 40k monthly income and would have to be done with 21 days or more remaining on permitted to stay stamp.

You can take marriage certificate/copy of wife ID card/home register and perhaps a note from her asking for visa to any Consulate outside Thailand to obtain a single entry non immigrant O visa and could do a second time for the next 90 days. If you can show 100k in bank account and have the above proof you may be able to obtain a multi entry in KL. Perth would be the closest place for multi entry without financial proof.

The only way such an entry could be changed would be for a one year extension of stay to live in Thailand with proof of 400k in Thai bank account or 40k monthly income and would have to be done with 21 days or more remaining on permitted to stay stamp.

I thought you could not get the one year extension of stay based on marriage with a tourist visa....was told it had to be a Non-Imm O

You can take marriage certificate/copy of wife ID card/home register and perhaps a note from her asking for visa to any Consulate outside Thailand to obtain a single entry non immigrant O visa and could do a second time for the next 90 days. If you can show 100k in bank account and have the above proof you may be able to obtain a multi entry in KL. Perth would be the closest place for multi entry without financial proof.

How sure of a thing is it that I could get multi entry in KL with the proper documentation and 100K in Thai bank?

Please do not quote/post without showing which is which.

You can convert a tourist visa or visa exempt entry into a non immigrant entry using TM.87 or TM.88 and paying 2,000 baht if you have 21 days or more remaining and present normal extension of stay proof. This is done at Bangkok and some other offices.

I am very sure that KL will issue multi entry for marriage with stated documents - many people have done so recently.

You can convert a tourist visa or visa exempt entry into a non immigrant entry using TM.87 or TM.88

Make that TM86 and TM87 (I know you knew that).

But, I now learned what a TM88 is: for Visas on Arrival.

86/87 is right - mind may know but fingers like to type other characters at times. Thanks for making the correction.