Is it possible to extend in Korea without benefits?

If you are on assignment instructions you will not be able to extend your overseas assignment. Any extension must be submitted through your chain of command and approved by HRC (this only applies if you are not on assignment instrs).

Have you tried your Branch Manager? Prior to my retirement I extended my DEROS to the start of my terminal leave but I had to get the go ahead from Branch. Also, are you already on assignment? That plays a very big part in whether this will be okayed or not. If you are, with no emergency or anything to substantiate a change, your chances of it going thru are slim. Sorry.... but I've seen many Soldiers try it without a specific reason only to watch them pack up and move on to their next assignment. I wish you luck tho!

Have you talked to your career counselor (I think the career counselor is the one to talk to)? The two times that I was there, there were soldiers who extended for a year or two because they liked Korea. Just checked the internet, it's called an AIP "AIP allows soldiers to extend their tours in 12-month increments, but no more than twice for a total of 24 months." Check with your career counselor, he/she will have updated information about it.