What can be done to a Soldier who refuses to study for the board because he will be ETSing next year?

Nothing...let him ETS.

Why is everyone recommending a counselling statement? Lack of desire to study is an indication that the SM doesn't have at least one of the requisite traits for promotion. It's the responsibility of the SM to choose whether to attempt promotion. Some people just don't want the added responsibility that goes with a promotion. I had a SM work for me for three years. She reported in as an E1 and left as an E5. Had she not gotten married and decided to follow her husband, I'm sure she would have continued on upward. Conversely, I had two others in the same office that were E5 when they started working for me and still were E5 a couple years later when I transferred out. They were quite happy with their level of responsibility and didn't want to move up to do my job. Their choice and no skin off my nose as they did a good job as an E5.

Force a soldier to do something and you will not only lose their respect but possibly any extra effort they put in even when you aren't looking. If they have plans for the outside and are deadset on ETS then let them. Do a CYA counseling saying you offered and they declined but no negative repercussions will come of it. You may just find when you get out of uniform and ets or medsep yourself that they will end up being a very valuable asset in the civilian side of things.

Why should anything be done? He doesn't want to go before the board, he plans to ETS, end of story. Do a CYA counseling statement, explain his options, summarize his own decision. He signs, you sign, all done. Don't force him to do the board, don't hassle him about it.

I dealt with this on several occasions. I left the option up to them. A few went just in case but others chose not to. On this decision it's really up to the SM not you. Even if you think they are a great trooper, they may have other plans for their lives.

Ensure he has the support necessary to do his job until you release him to ETS separation counseling. That’s what should be done for him.
Why does someone choosing to let others compete for a slot they don’t want to occupy, knowing they plan to get out need negative consequences. Bottom lining it, they’re looking out for the needs of the service by letting another motivated member fill that slot. It would be worse if they selfishly took the slot and slowed the potential development of another leader or even worse, influenced that potential leader to leave the service also by blocking that opportunity.

Nothing. It is not Mandatory to go to the board. It's his call...if he wants to get out promote a soldier that is staying in...why waste the slot in the MOS.

I don’t know much about it so i’m Not saying this is the correct course of action but what about a dec statement? Would that not stop the chain of command forcing the SM to go to a board and also force them to consider if they really want to get out or not? If they choose to do the 4991 then they can’t re enlist and will see their contract out to completion but will not promote, attend schools or go to a board. They will get what they want and will have to consider if they are true LT getting out now. I’m not 100% sure that’s exactly how it works but it’s my understanding so don’t slam me if i’m Wrong.

Well it’s their choice. But I’d rather say , as I did when I retired “ I was on the promotion list and declined to be able to retire as scheduled, it was right for my family”. Sounds better than not even trying. And as has been said already, minds change nice to knowing staying brings promotion and extra couple of bucks.

Why force them? That is my question. If people don’t want to stay in, it because of a larger Army leadership problem than a promotion problem. Let them ETS.