I would like to start an LLC to run this. 

Since there is no custodial requirement for the 401k, you don't need the additional expense and administration of an LLC to obtain checkbook control.

I have done this in the past, but with individual members on the first deed and the holding company LLC as the second.

They each Househacked a multi on Boston,(Quincy and Southie) using their FHA loans and then the plan is to refinance the properties into a LLC where they each of them own 50% once they have enough equity for the refinance and they’ll clear the PMI at the same time. 

If this entire property was a rental property, I would have probably just created an LLC and put the mortgage and deed in the LLC's name. 

He thinks we could turn it into an LLC and create a rental (ADU?)

Does anyone here know how to properly structure their LLC to get the most amount of business credit?

I had it under my Personal name and this property is also still in my name which I hope to put into an LLC as soon as I find the proper bank and possibly do it prior or after closing on the refi.

Hi, I have a duplex rental for 4 years but I have never set up an LLC, so I claim that as passive income on the schedule E.

Will you set it up as an LLC or an S-corp?