I thought at one time I read that the O-A Retirement visa had to be funded from sources outside of Thailand. But I also read a lot of posts that just indicate that you only need 800000 that been in a Thai bank for 3 months with no mention as to the source of income.

So theoretically, lets say that I've been living and working (and paying taxes) in Thailand for 10 years, and I decide to retire. My funds have been made within the country, but I've saved the required 800000 baht to qualify for the visa. Is the source of the income going to be a problem?

I think that will be OK. However, if you start this in Thailand, you will NEVER have an O-A visa. An O-A visa is only obtained in your home country, and you do not need it either. Starting in Thailand, you will be getting extensions based on retirement. The bank option is 800K seasoned for two months for the first extension, three months for subsequent ones. Before getting the extensions, you first do need an O visa (O-A not needed). The O visa can be obtained in Thailand as part of the process of getting the extension (Bangkok and Pattaya) or in a neighboring country (Malaysia, Laos).

Edited August 27, 201015 yr by Jingthing

As JT said you should be ok and you will probably be getting an extension of stay, not a O-A Visa.

The requirement to start inside Thailand is non immigrant visa entry - it does not have to be an O visa entry to extend for retirement. If you were working on a B visa you just extend on the basis of retirement with no need to change visa entry.

Even when they did check for foreign origin of funds did not hear anyone retiring from employment inside Thailand having an issue so expect they allowed local funding in that case even though it was not officially stated.

Thanks all for the information!