Company in another state

I have a company in Georgia that is a corporation. I want to form another corporation in Michigan, but I want it to be under the corporate company in Georgia. The names will be slightly different. My question is, how do I register the company in Michigan with the IRS. Does it have to be a corp or something else. The Board of Directors will oversee both companies. Open to suggestions.

First of all, you should ask yourself if you really want two separate companies. You may just want to have the Georgia company do business in Michigan -- to do that, you have to get a Certificate of Authority from the Michigan Dep't of Licensing & Regulatory Affairs.

But, in answer to your question, if you really want to do that (and there are plenty of reasons not to), then (1) you would form a Michigan corporation and sell your shares in the Georgia corporation to the Michigan corporation (presumably for shares of the Michigan corporation). Then, you'd name each of the directors from the Georgia corp as directors of the Michigan corp.

My question is, how do I register the company in Michigan with the
IRS.

By "how do I register" you mean what? You get an EIN using SS-4 (or online). As to the tax filings, you may want to group them together as a controlled group, or QSub if your parent corporation is a S-Corp. You really have to discuss this with your tax adviser.

Does it have to be a corp or something else.

Depends on your needs, really. You need to take this question to your tax adviser and lawyer. You can just qualify your Georgia corporation to operate in Michigan, but if you think you need a separate entity - you need to identify the reasons, and then decide which of the possible options addresses them the best.