What documentation is required for the non-immigrant O retirement visa extension using bank deposits and pension income in Thailand?

Sadly, it is one of the most difficult ways to show proof of funds for a retirement extension

First keep in mind even though the "combination method" is a valid means to show proof of funds in the immigration rules for extensions based on retirement not every office allows you to do it (and there's nothing you can really do if they say no 🙁 )

Some offices that allow it require 400K baht banked (meaning 50% of the banked money requirement) 😮

There are two ways you could show the rest of the money via monthly income;

1 - transfer in from internationally the same amount, each month, every month for the previous 12 months so that when those transfers are combined with the banked money it totals 800K

example bank 200k <- transfer in a minimum of 50K baht each month every month for the previous 12 months. (12X50k=600K+200K=800K)

example bank 400k <- transfer in a minimum of 34K (about) each month, every month for the previous 12 months. (12X33,500K=402K+400K=802K

2 - IF your embassy issues the affidavit of income from abroad you'd use that notary letter to show you get the monthly income.

Remember you have to total 800K baht for the year with banked money and either the embassy letter or the monthly transfers <- AND on monthly transfers they will not count each one separately 😮 they will find the transfer that had the least amount transferred in during the year and use that times 12 to get the income by transfer amount.

Also all transfers have to show as international origin