Run the common rent comps and compare that to your PITI and overall costs to analyze cash flow.

I'm currently looking at a few potential single-family fixer-uppers (some in Worcester, Taunton, and near Dorchester), and I could really use some expert advice on current rehab costs for different scopes of work.Here are some numbers I've gathered from my contractor friends.

I definitely am more interested in the syndication route than flipping but I know house hacking could be another great route to go early on.Right now I am able to save a lot of money as I am still living at home, rent free, and my monthly expenses are very low (about $300). 

Ground-up development is not low-risk however, with a few uncommon exceptions.

I assume that I don't actually have to pay the capital gains until the principal repayment exceeds my cost basis, which on an amortized loan would be quite awhile (assuming they don't refinance and pay me off altogether).

As long you clearly identify and track the expense per property (and you can do that in Quicken, with properties, categories and subcategories, or in Quickbooks), you’ll not need CCs and accounts per properties.Here are some graphical diagrams to help you on this quest (or confuse you further): - Asset Protection Decision Diagram - to help assess the need for asset protection, and what to implement: https://www.biggerpockets.com/files/user/CosIorg/file/asset-protection-decision-diagram - Asset Protection Onion Diagram - what, when, and at what cost one should implement in terms of asset protection - https://www.biggerpockets.com/files/user/CosIorg/file/asset-protection-onion-diagram-v2 - What is needed for complete asset protection OR the domains that need to be intersected to find asset protection

Next, what is the cost of the renovation vs higher rent delta? 

Just understand that one mistake can be very costly.  

They've performed well and expenses are extremely low.

So, the family member is pocketing cash and guaranteeing a stable cost of living for themselves basically locking in their future at a time when values are high.