Hi! I'm a 16-year-old student living in Bangkok, Thailand.

I currently study in an international school, in 11th grade, and I was wondering if I would be able to transfer to a US high school during or after the year?

So if I were to move now, would I have to wait until summer, then join at 12th grade? Or would I have to retake 11th grade; is any of these options even possible?

If this helps answer the question: I am a US citizen, with no US address.

It all depends on you past grades, the courses you've taken and passed successfully and whether you will be attending a public or private school and in which state you will be living while you are going to school. So, ask the administrators of the school or schools where you are applying as they will be the ones who are best qualified to answer your questions.

I've finished IGCSE's, and I'm currently doing the International Baccalaureate, or IB course.

This is a "Travel Forum". People here can't give you definite answers. Contact School administrators or at very least Google "Attending High School in USA".

For starters try looking here: https://www.usa.gov/study-in-us

Talk with your school in Bangkok. They will have the information you need. They can also make arrangements for your do do and exchange year or something similar.

As a travel forum we cannot be of much assistance.

well, of course you CAN do such a thing, people who move to the US legitimately (or expats returning home or military) are allowed to enroll their kids in public schools immediately, they don't have to wait until the next year.

I can't imagine why you think you'd need to retake 11th grade if you are getting a decent education. We have an international bac school near me, actually, I suggest you look into those as they should be on the same level.

Of course, a kid cannot just up and move to the US on his own, you aren't even mentioning HOW you intend to do such a thing or where or with whom you intend to live. I think that's rather an important issue.