Can I do a border run after 90 days in Thailand to extend my stay for another 30 days?

For best results - use a visa agent. Sure you could save a few dollars doing it your self but agents will help to mitigate risk.

Depends on your past history in Thailand I think.

did one after 90 Days, but customs asking me what i‘m doing that long in thailand. i said will make a retirement visa, then they let me in. they said, please dont come back without the retirement visa…

that depends on if the 90 days weren't all achieved by two visa exempt entries plus one 30 days extension. Then this will be your third visa exempt entry and you will probably get pulled aside. You need to tell us how you got the 90 days stay - did you use a 60 days tourist visa plus one extension? In case you did so, then the answer is YES, you will be able to do a border run and a visa-exempt entry. In case you enter by air, make sure you got an onward travel proof out of Thailand within the 30 days, as the airline might ask for upon check-in

That's not excessive. Should normally work.

Just did one night kl.

Extra 30 days. Just make-sure you can show flight ticket home! Was asked lots of questions returning through phuket immigration!👍

@Rob ******

He can do a border run and get a 30 days exemption anyway. If he has done 90 days he’s probably on a tourist visa.

yes i did one after 90 days

yes

Yes as long as your passport country allows visa exempt entry.