I hold a Non-Immigrant O visa vaild up to October 2011 entered February 23rd and was granted an extension of stay for medical reasons up to July 4th.

I am an overseas worker on a 28 x 28 rotation.

I need to go to Singapore for a day so I understand that I will need to submit the TM-8 from asap.

I will then be leaving for 4 weeks from July 9th.

My question is does the Immigration department usually accept a one day turn around on my exsisting visa?

You have a multi entry non immigrant O visa valid for entry until October 2011? If yes you will just use that for your return from Singapore. No need for re-entry permit that would only allow you to stay until July 4th in any case.

Do not understand your question of a one day turn around unless you are asking about re-entry permit (which is normally done as you wait).

You question is a bit difficult to understand, maybe it's me. If you have a multiple-entry non-immigrant "O" visa valid until October 2011 then a trip to Singapore is no problem. A re-entry permit will only be valid until 4th July, the expiration date of your extension. Immigration issues re-entry permits on-the-spot, certainly within a couple of hours, the fee is 1,000 baht for single re-entry.

Does that mean if I go out and return next day I will get 3 months as usual??

The fact that it says I need re-entry permit is confusing to me and I appolgise if my explanation is unclear.......

Yes you leave and return for a new 90 day permitted to stay if you have a valid non immigrant O visa.

You had a medical extension of stay - that would be the reason for such a notice of need for re-entry permit. But you will not use that for new entry so not needed.

It's all much clearer now thanks!