As the term Tambon (Subdistrict) Administrative Organization is quite lengthy, it has become usual to refer to these by the acronym. However, two versions for the acronym are equally commonly used - either TAO or SAO depending on whether one translates the word Tambon or not. Even in scientific papers one can find both versions, and though it might be selection effect or a just a delusion it seems to me that so far the acronym TAO is the more common one. Which is of course the reason why I use that one here as well as in the Wikipedia articles. It is also in line with the well-known acronym OTOP, where the word Tambon is also used untranslated in the English acronym.
However it now seems to me that SAO will become the preferred acronym, though I haven't found it anywhere on the websites of DOPA or similar authorities as the official recommended acronym. The reason why I believe this comes from the fact that I recently have seen the first highway sign pointing towards a TAO office. Especially the green signs now always use the RTGS transcription standard, so I tend to believe if they write SAO on such a sign it should be the standard English term as well. Sadly I cannot give a photo of that sign as I only noticed it when looking out of the driving car, but it was somewhere near Bang Bua Thong on highway 9, the circle highway around Bangkok.
In Thai this is of course no problem - องค์การบริหารส่วนตำบล is also a long word but it always abbreviated as อบต (O Bo To).