Short version: if the LLC will continue to be taxed as a corporation (C or S), no new EIN. If it will be taxed as a partnership or disregarded entity, you need a new EIN (and have a taxable event).
https://www.irs.gov/businesses/small-businesses-self-employed/do-you-need-a-new-ein
Corporations
You will be required to obtain a new EIN if any of the following statements are true.
- A corporation receives a new charter from the secretary of state.
- You are a subsidiary of a corporation using the parent's EIN or you become a subsidiary of a corporation.
- You change to a partnership or a sole proprietorship.
- A new corporation is created after a statutory merger.
You will not be required to obtain a new EIN if any of the following statements are true.
- You are a division of a corporation.
- The surviving corporation uses the existing EIN after a corporate merger.
- A corporation declares bankruptcy.
- The corporate name or location changes.
- A corporation chooses to be taxed as an S corporation.
- Reorganization of a corporation changes only the identity or place.
- Conversion at the state level with business structure remaining unchanged.
