In 2020 my business was as single member LLC. So I simply filed a schedule C.
But in 2021, we added a second member.
Basically, you have to close the single member LLC and open a new multi-member LLC. So you'll be filing a final SCH C on the 2021 taxes for the single member LLC. All inventory and assets (if any) in the single member LLC will need to be removed for personal use. Then when you start the first 1065-Partnership/Multi-member LLC tax return, those assets will be your initial contribution to the partnership/multi-member LLC.
I would highly suggest you seek professional help for your 2021 taxes for both your personal taxes with the final SCH C and what will be your first 1065 return. This is particularly important if your state also taxes personal income, as you're dealing with a change in the type of business entity you have. The tiniest mistake can be costly when such mistake is realized later down the road. Professional help for at least the 2021 taxes will significantly reduce the likelihood of such mistakes occurring.
