Yes, you are filing two separate short year business returns. The change from multi-member LLC (taxed as a partnership) to single member LLC (taxed as a sole proprietorship) occurring on March 27 causes the multi-member LLC to file a final short tax year return for the period from January 1, 2020 - March 27, 2020 issuing Schedule K-1s carrying to the Sch E page 2 of the taxpayers' Form 1040. The new single member LLC's tax information will be reported on Schedule C on the owner's personal income tax return and would cover the period of time from March 28, 2020 through December 31, 2020.
The full year income and expenses of the business operations will need to be broken down between the two periods by date, because they are changing the entity to two separate businesses and filing two separate entity business returns for the year, one on Form 1065 (multi-member LLC taxed as partnership) and one on Schedule C as sole proprietorship.
