What if they all decide to leave, can you carry the mortgage, etc. while renovations happen? 

To me, I don't see why anyone wouldn't do cost segregation even if it ends up being held as a carry forward loss. 

@Chris Seveney I was a Transactional Lender, single closings, buyers lender accepted seller carry back.

Instead, they could offset passive income or be carried forward.

Have someone who doesn't live in the home walk through and itemize the things that need to be fixed or improved.

Cleaning fees and other line items are revenue; its just a way of parsing out revenue to try to reel in customers. 

, any personal items to be removed/locked up etc? 

Hello BP,My parents recently inherited a timeshare that carries with it some formidable annual maintenance fees.

The next line item down under terms states: "Any notice to terminate this tenancy must comply with the applicable legislation of the Commonwealth of Pennsylvania (the "Act").

But if the replacement property has less value in section 1245 items, you do have to compute the difference (which pretty much requires a cost seg study on the acquired property), and then you have 1245(b)(4) recapture on the difference.