James Bynum - I don't know why you would be "raising red flags" by advertising your home with its accurate square footage.

They are just one source of information and it may not be accurate or may not even apply to you, your personality/skills/abilities, and particular goals.  

Selling one (to repay hard money), and then live in the other while collecting rent from the other tenants.Is that an accurate assumption?

The boundaries of a neighborhood can be larger streets, tracks, parks, etc.A house as close as possible in features (beds, baths), size, etc.Using the same financing method, with an arms-length transaction.Once you've found the right comps, then you have to make adjustments to them based on all of those features to get an accurate value for your property.I used to use a spreadsheet for that, until I built this tool: www.reikit.com/compsThe tool uses Zillow data for lookups, but usually I go in with my own set of comps from my realtors then use the tool for adjustments.The hard part is getting the comps, though, and MLS is always going to be king.Cheers!

I think the sentiment behind Steve's idea is accurate, even if his actual statement about it is not really quite.

If you've already got a lot it would be more accurate to call a local contractor.

But then I go to the next level to attempt to be a little more accurate.  

You will definitely need a detailed scope of work to get accurate estimates. 

The best way to ensure correct filing is to have accurate bookkeeping and records.

I'm not 100% sure, maybe someone else can verify if that statement is accurate.