How do you write my commander regarding toxic leadership in my unit?

Why write a letter....own it, go to him/her address your issues face to face and if he doesn't get it, you have many other options to influence change. Next higher Cdr, IG, etc.

SPC (Join to see), I see that you mention "a Commander" so are you writing it outside of your COC?

I would caution you to become fully informed as SPC(P) Micah Lavigne stated and advised.

There is nothing wrong with bringing things to the attention of the uppers; they need that from time to time. I once wrote my Company Commander a list of things that I thought could be improved upon in the Unit and he actually took the time to discuss every point with me. Of course some were validated and others were not.

If you truly believe that there is an issue then it needs to be addressed. At a minimum they can move you outside of the situation.

My advice would be to try every level of your chain of command prior to getting to your commander. If not, you are very likely to perpetuate the toxicity and focus it upon yourself.

First of all. Use your Chain of Command. Go to the next higher leader/supervisor. Give the leadership a chance to correct the problem. But if the problem is within your immediate COC you can always use your commander or 1SG's open door policy. Just make sure the problem is real and it isn't just that you don't like your Squad leader or you think they don't like you. Leaders are not there to be your friend. I've seen so many young troops get their feelings hurt and then start complaining about everything, to everyone that will listen. The important thing is to let the COC do it's job before you jump straight to the CO.

Do you not have the I G's office any longer?

First I would research the Army Regulation's Definition of Toxic Leadership, then I would see if it is true (sometimes its just a tough as nails Leader). Then I would go to someone in your immediate Chain of command (starting with the lower levels of your NCO support channel and tell them your thoughts. If the NCO is a great leader he may help you or stand by you as you see the next level to deal with the Toxicity.

I had an experience with Toxic leadership back as a private. I used my NCO support Channel to ensure I did it correctly. and when I finally went to the appropriate level of leadership the said Toxic Leader was removed from his position.

Its a slippery and uphill battle, and you have to be sure you are correct and that your leadership or a leader that knows the issue between you and the toxic leader supports you and helps you address the issue.

But if you need more information I would contact legal dont give names just ask for information on toxic leadership and reporting requirements.