Can I get a COVID extension in Thailand if I can't return to China but have a US passport?

That's what I did. You need a letter from your employer in China stating you can't return.

@Raymond *****

I think it's totally gonna be up to the immigration office and officer. BUT believe me you CAN leave the country if push comes to shove so that's not even a debatable issue. Now you might not be able to go where you want to but leaving isn't the problem.

The regulations says either the country stated by passport or residency. The challenge in a case you describe is living long term in a foreign country but most likely do not possess legal status of residency in that country. If that applies to you you'll need to find a way to proof with papers that your life is centered around the country your residing in, even you don't have legal residency. With a documented local work permit and the visa matching that, it should be feasible. Translation provided. If you lack those, you need to find other ways to proof it. Embassy might help (not likely), bank accounts, rental contracts, electric bills etc can help. Being prepared and bring a stack of papers can help to convince an immigration officer, just be prepared if you encounter is first denial and go on and try again.

Id just ask for the extension and not say a word unless you are asked, then answer short sentence.

May I know who is eligible for 90 days covid extension? Is it for certain countries only ?

You can try to explain your situation if asked by Thai Immigration as to why you cannot return to ...China.

I'm assuming you entered Thailand on an USA passport. IF the immigration office asks for proof, you would use ONE of the following three documents:

A letter from your embassy saying you can not return, OR;

A print out from your embassy website saying they don’t issue the letters, OR;

A print out of a letter from the embassy saying they don't issue those letters.

The US Embassy has a notice on their website saying they do not issue the letters. You would submit a screenshot of that as proof, if requested.