Since the LLC is just moving from one state to another, and not changing its structure or tax status, a new Tax ID number shouldn’t be required. The LLC would need a new Tax ID number, for example, if you terminate the LLC in one state and then start a new one in another state (or even the same state, for that matter). I haven’t seen the IRS impose new Tax ID number requirements on an entity like an LLC that moves from one state to another. In fact, applying for a new Tax ID number would likely confuse things.