I believe you would.
https://www.irs.gov/businesses/small-bu ... -a-new-einThe LLC section doesn't have an example that matches your fact pattern, but the partnership section does.
Partnerships
You will be required to obtain a new EIN if any of the following statements are true.
-You incorporate.
-Your partnership is taken over by one of the partners and is operated as a sole proprietorship.
-You end an old partnership and begin a new one.
You will not be required to obtain a new EIN if any of the following statements are true.
-The partnership declares bankruptcy.
-The partnership name changes.
-You change the location of the partnership or add other locations.
-A new partnership is formed as a result of the termination of a partnership under IRC section 708(b)(1)(B).
50 percent or more of the ownership of the partnership (measured by interests in capital and profits) changes hands within a twelve-month period (terminated partnerships under Reg. 301.6109-1).I would just run a trial balance up to the date that it became a SMLLC. That's the partnership's final short-year data. Then run a trial balance from the date it became a SMLLC to year-end. That's Schedule C data for the individual. No need for reporting the individual's loss on the partnership return and phantom offsetting income.