Working interests in oil and gas wells and royalty interests are considered to be like kind for real estate. 

Please validate that your bank offers 90% on a HELOC, that seems very aggressive (yet awesome if they can do it).   

Your permitting dept I’d the only valid source to answer this question. 

.- Validates identity, you can match name to the photo ID they provided.

How long are pre-approvals typically valid for?

Older units will use more resources (gas/electric/water), which is a cost only you will incur.

-Roof ( find out when the roof was placed, the condition) - Electric/ Gas ( find out metering situation) if they are not separately metered that will cut into the cash flow. - Windows( for multi-unit properties if there are a lot of windows that need to be replaced this can costly.) - Overall repairs needed In conclusion, research the area and find a good property manager or inspector and make sure they look more into the things above and anything you know of that is a high-cost repair! 

Closing guy said that the language in the main contract that referenced the assign-ability was ambiguous but he felt that the take away was the assignment wasn't valid. 

Property DetailsCurrent Mortgage Balance: $113kCurrent Estimated Home Value: $180kYears Bought: 2013Interest: 30-year fixed 3.99% (No PMI using special loan program for just 15% down)Analysis: Income Current Lump $50k Principal Payment Paid Off Mortgage Rental Income $ 1,500.00 $ 1,500.00 $ 1,500.00 Laundry Income $ - $ - $ - Storage Income $ - $ - $ - Miscellaneous Income $ - $ - $ - TOTAL Monthly Income $ 1,500.00 $ 1,500.00 $ 1,500.00       Expenses       Water/Sewer $ - $ - $ - Garbage $ - $ - $ - Electric $ - $ - $ - Gas $ - $ - $ - HOA $ 240.00 $ 240.00 $ 240.00 Lawn/Snow $ - $ - $ - Vacancy $ 150.00 $ 150.00 $ 150.00 Repairs $ 15.00 $ 15.00 $ 15.00 CapEx (Replacing Things) $ 125.00 $ 125.00 $ 125.00 Property Management $ 150.00 $ 150.00 $ 150.00 PITI $ 778.67 $ 475.15 $ 180.00 Other Expenses $ - $ - $ - Total Monthly Expenses $ 1,458.67 $ 1,155.15 $ 860.00       Cash Flow       Total Monthly Income $ 1,500.00 $ 1,500.00 $ 1,500.00 Total Monthly Expenses $ 1,458.67 $ 1,155.15 $ 860.00 Total Monthly Cash Flow $ 41.33 $ 344.85 $ 640.00 Total Annual Cash Flow $ 495.96 $ 4,138.20 $ 7,680.00       Cash on Cash Return       Down Payment $ 30,000.00 $ 30,000.00 $ 30,000.00 Closing Costs $ 2,000.00 $ 2,000.00 $ 2,000.00 Addition Lump Principal Payment $ - $ 50,000.00 $ 115,000.00 Miscellaneous Initial Costs $ 3,000.00 $ 3,000.00 $ 3,000.00 Total Investment $ 35,000.00 $ 85,000.00 $ 150,000.00 Cash on Cash Return 1% 5% 5%Any helpful insight and/or constructive criticism on the math and assumptions on this analysis would be greatly appreciated.

@Mike Villela, All of your post-sale options are valid and good to pursue.