How accurate is the 50% rule?

Do you want your quarterback to be accurate or have a strong arm?

The IRR is only truly accurate when an asset generates no interim cash flows, or when those interim cash flows can actually be re-invested at the actual IRR.

Most advertisements for real estate, whether in print or via MLS typically have a line that information is deemed to be accurate but is not guaranteed.  

Who can I check it with to get the most accurate answers ?

The list I get now is much more complete and typically more accurate than what I was pulling on my own.So I would suggest you investigate the time associated with pulling them on your own and the money cost of purchasing one from a reseller (assuming you have that option in your area).

That way, if something goes awry, you have room to wiggle.Assuming your exit price, holding, and rehab are correct, here are my thoughts:Exit: 100K (your number)- Selling Costs (8% = $8K)- Purchase Costs if paying cash (1% = $1K)- Holding Costs $1200 (your number)- Rehab $10K (your number)- Minimum Profit Target 20% Exit = $20K-------------------------------------------------------Max Offer: ~$60KI like this formula better than the 70% rule in some cases because fixed costs can vary and you can accurately plan your estimated profit.  

Stopping here and assuming these numbers and rates of depreciation are accurate...that leaves you with $56,000 worth of house that still gets depreciated over 27.5 years.  

You can also use Zillow.com's estimate as a quick back of the envelope but those numbers aren't always the most accurate.

Nothing wrong with the cash on cash return, and as I get more accurate numbers on a deal, I do calculate the cash-on-cash and make sure it looks OK.I will say, however, that even as I get more accurate numbers, I don't lower my expense ratio below 40%.