For the benefit of a newcomer:

There are at least two ways to get a non-im O visa.

One is by marriage to a Thai. Bring your marriage certificate and a copy of her ID to the consulate of your choice and get the visa.

Then, to extend it, you wait until you're on the third month of the visa to visit the cheerful folks at immigration.

It's been a long time since I've done this, but I think you need a recent (same day?) letter from a Thai bank showing that you have 400,000 baht in the bank.  You may need to copy your bank book as well.

I think they also want to see photos of the happy couple at home and in front of the home.

You then get to return in six weeks.

Another way is to be 50 years old.  When I did this, it was age 55 in the home country or age 50 if I applied closer to Thailand.  I applied in Kuala Lumpur.  I had to show a letter from the bank stating that I had 800,000 baht in the bank. This letter was in English.

Then, I needed a letter in Thai to extend the visa.  I also needed a health certificate.

I have never heard of anyone having trouble entering, by air or land, with a non-im visa.

I expect to here from those with more current info.

"I have never heard of anyone having trouble entering, by air or land, with a non-im visa." - There have been a couple of reports from the South, that people on multi-entry Non-Imm O have been refused entry at a land border and been told to fly back into Thailand.

1stevec wrote:"One is by marriage to a Thai. Bring your marriage certificate and a copy of her ID to the consulate of your choice and get the visa." - And copies of her blue book pages. Plus, the spouse needs to sign all copies too.

"I think you need a recent (same day?) letter from a Thai bank showing that you have 400,000 baht in the bank.  You may need to copy your bank book as well." - You forgot to mention the 2 month seasoning period for the money and the option of having a 40k a month income.

"I also needed a health certificate." - Not sure where you extended? (Possibly Samui?) There is no requirement for a medical certificate to get an extension of stay based on retirement.

I extended in Chiang Mai. The requirement was very real.