I was given a one year multiple entry Non-immigrant visa Category O last July (2013) in the UK and arrived in Thailand 30 July where I was given a 90 day stamp.

Just before the end of the 90 days I went over the border to Cambodia at the Poipet border crossing and got a Cambodia visa.

I stayed there an hour or so then came back into Thailand where they gave me another 90 day stamp.

BUT (Thai Officials) stamped my multiple entry visa as USED.

I have only a couple of weeks before the end of this second 90 day period. Can I go to Cambodia again and return to Thailand?

In other words can I re-use multiple entry Non-immigrant visa Category O (stated to expire 25 July 2014) even though it has been stamped USED?

If not what can I do?

Thanks for you help.

I have never had the used stamp put on until the year actually ended. I suspect that it is now done. I would go to your local immigration office and see if you could get an extension on it. Most likely you will have to go and pay for another visa.

looks like they stamped it by mistake as it is clearly still valid.

Pop along to Immigration and see if they can certify it still valid.

Find it interesting that when I asked the Thai Consulate in New York to stamp my many expired O-A Non Immigrant Visas as used they stated that they did not have a USED stamp so could not do it

The consular officer understood why I wanted them stamped since I have so many so his solution was to draw a single line across the expired visas so I think the OP's USED stamp was locally procured or maybe only available at land border crossings

As said it appears to be a mistake and is now officially invalid. If you use the same crossing and point out, in good mood, that it should still be valid expect they will allow a new entry but at another entry point suspect it would not be allowed. I would point it out before making the crossing but in worst case you could still obtain a visa exempt entry of 30 days.

If you are prepared to extend your stay yearly it should not matter as visa does not have to be valid for such - you are extending your permitted to stay not the visa.

I have never had the used stamp put on until the year actually ended. I suspect that it is now done. I would go to your local immigration office and see if you could get an extension on it. Most likely you will have to go and pay for another visa.

Hi and thanks for the reply. When you say "local immigration office" what does that mean? Does Thailand have local immigration offices then? Where are they? In every Amphor of only the Jangwat?

I live in Pak Chong - Jangwat is Nakohnrachsima.

The local immigration office would be wherever you would go to do your 90 day report, or extend your visas. I am not sure where they are all, but typically the larger provinces have them. I don't think that every province has them though.I would think that Nhakornrachasima would have one

Nakhon Ratchasima (Korat) Immigration Office
—— Postal address —— Immigration Office 7 Mu 7 Dan Kwian Amphoe Chok Chai Nakhonratchasima 30190

https://maps.google.com/maps/ms?hl=en&ie=UTF8&msa=0&msid=214923170432669428134.000465f03d84d91df360b&t=h&z=6