I have a relative who is over 50 years old with a tourist Visa. She would like to change her T.V. for a Non-Imm O based on retirement. She does not have pension income, but she has investment income coming (capital gains from stocks and other investment such as mutual funds).

For this year, her income averaged around THB 115,000 per month. She uses an ATM card from a foreign bank to widthraw funds in Thailand, she does not have a Thai bank account. The Canadian Embassy in Bangkok said they would be comfortable to give her a letter confirming her income.

So the question basically is:

Can she go to the immigration with a T.V. (she is getting her T.V. extension stamp next week) and apply to get a Non-Imm O by just showing the Embassy letter? This is in Chiang Mai btw.

Unless there are Chiang Mai specifics (you need to ask the office involved) she should be able to convert her visa if she applies with 21 days or more remaining on the current permitted to stay stamp (after her 30 day extension starts in this case). She will need the Embassy letter and 2,000 baht fee and a current 4x6cm photo. She will likely be told to return in two months to apply for/obtain the extension of stay and she should open a bank account and have that passbook and a letter from bank available for the final extension (although it is possible Chiang Mai might not require that).