I travel quite a bit and usually am not in the same city as my last check-in. Obtained my 12 month extension ( marriage based ) in Pattaya and my last check-in was in Chiang Mai. My next check-in is on April 11 and I'll be in Buriram where I've been for the last 3 weeks.

How do I report? An option I assume is to cross the nearby Cambodian border but I don't have a re-entry permit at the moment. Can I obtain a re-entry at the border?

Next year I need to stop being so cheap and get a multi-entry even if I don't intend on leaving the country. It seems I always end-up leaving for a few months regardless of my intentions.

Thanks!

You can report by mail, at the office where you did your extension.

Alternatively, you can get a re-entry permit at that office.

Notification by registered mail

1. Copy of all passport pages (up to the latest arrival stamp in the Kingdom or latest visa stamp)
   
2. Copy of arrival/departure card TM.6 (front and back)
   
3. Previous notifications of staying over 90 days (if any)
   
4. Completely filled in and signed notification form TM.47
   
5. Envelope with 5 Baht stamp affixed and return address of foreigner for the officer in charge to send back the lower part of form TM. 47 after having received the notification. This part must be kept for reference and for future notifications of staying over 90 days.
   
6. The above mentioned documents must be sent by registered mail and the receipt of the registration kept by the foreigner.
   Send the mail before the renewal date 7 days to your own immirgation office
   

Many thanks Mario. I'm going to post it tomorrow and if I don't have anything back by April 5, make a trip to border immigration office at Kap Choeng ( near Buriram).

Is is my understanding that I don't have to leave country and can just do my 90 day check-in at the border. Am I correct?

Thanks again!

The report should be done at the location you are registered as being (in most cases that will be where you obtained your extension of stay). Some other offices have accepted and some not - by law you must report your presence immediately when you move and most people do not do that.