I am hoping that someone here can clarify for me precisely what documents I will need to bring to Chiang Mai Immigration in order to apply to have my Tourist visa changed to a Non-Imm visa based on being 50 years of age. I know I need to do this while there are at least 15 days remaining on my Tourist visa.

For the financial requirement, I will be using a combination of income and money in a Thai bank account. I plan to get an income affidavit from the US Consulate this month (I know that they will stop issuing them at the end of the calendar year). Just to be clear, is it correct that the only document I will need to have notarized is the income affidavit? Will I need to show other supporting documents re: income at Immigration? And will Chiang Mai Immigration keep my income affidavit when I submit it, meaning that I will need a second one when I apply for my one year extension in March? Would they allow me to submit a copy for the extension, because they will have the original in their possession?

Regarding the money in the bank, I can show my Thai bank statements/bank book, and the receipt for the transfer of the money from the US to Thailand (using TransferWise) more than 60 days prior to the application. Will I also need a corroborating letter from my Thai bank branch, or anything else?

What else will they require, aside from passport & photocopies of passport/photos/application form? And how early in the morning should I plan to arrive and get in line at Chiang Mai Immigration in order to ensure that I will be seen? Thank you in advance for your help.