Scenario: an existing LLC, taxed as a sole proprietorship or a partnership, has an employer ID number. If the LLC later decides to be taxed as a corporation, does it need a new EIN?
This one is straightforward to answer. The answer is, no.
Here’s what the IRS says (look at the 4th bullet point):
You will not be required to obtain a new EIN if any of the following statements are true.
- You report income tax as a branch or division of a corporation or other entity, and the LLC has no employees or excise tax liability.
- An existing partnership converts to an LLC classified as a partnership.
- The LLC name or location changes.
- An LLC that already has an EIN chooses to be taxed as a corporation or as an S corporation.
- A new LLC with one owner (single member LLC) is formed under state law, does not choose to be taxed as a corporation or S corporation, and has no employees or excise tax liability. NOTE: You may request an EIN for banking or state tax purposes, but an EIN is not required for federal tax purposes.
From the IRS webpage “Do You Need a New EIN?”