I have seen recent contradictory information here on this topic. From https://thaiembdc.org/visas/ , the Royal Thai Embassy website in Washington, DC:

 

As one of Countries listed for Visa Exemption and Visa on Arrival, U.S. Passport Holders are not required to obtain a visa when entering Thailand for tourism purposes and will be permitted to stay in Thailand for a period not exceeding 30 days on each visit. (15-day stays if arriving by land-crossing). The period of stay may not be extended.

 

If this was fully covered elsewhere, my apologies; but if not, and if this is enforced as stated, a surprise may be in store for those expecting to get such an extension.

This look old since they still give 30 days VE at land borders. It wasn't the case for a short period. Since then they reinstated 30 days VE with a max of 2 per calendar year and they are extendable. VOA get 15 days that I think is not extendable but this doesn't affect US passport. 

Edited August 29, 20196 yr by Tayaout

1 hour ago, Ozziepat said:

(15-day stays if arriving by land-crossing)

Outdated, false. 30 days.

1 hour ago, Ozziepat said:

The period of stay may not be extended.

Outdated, false. One extension of 30 days is possible.

 

I'll ask mods to move the thread to appropriate forum.

Moved to the Visas forum. 

Visa exempt entry gives you 30 days and you can extend 30 days.

I did this today ????

 

I have also entered via land borders before (over a year ago) and always got 30 days and i have extended those in the past.

9 minutes ago, Jackie66 said:

I have also entered via land borders before (over a year ago) and always got 30 days

Yes, has been changed (back) from 15 to 30 days years ago (can't tell exactly when that was).

1 hour ago, Tayaout said:

This look old since they still give 30 days VE at land borders. It wasn't the case for a short period. Since then they reinstated 30 days VE with a max of 2 per calendar year and they are extendable. VOA get 15 days that I think is not extendable but this doesn't affect US passport. 

Correct. VOA no extension.

So then here is what should be a simple question with an acceptable answer: Where is there maintained one single online, complete, comprehensible, current, official version, in English, of Thai government-enforced rules regarding visas: types, conditions for qualification, application procedures and extension options - with all necessary details, costs, exceptions, exclusions, etc. Asking for a frustrated friend who understands the importance of compliance but cannot identify that with which one is expected to be compliant.