You can do 1 of two thingsEach month you can split your payment for your mortgage and report the interest portion as interest expense, and the principle portion reduces the mortgage (This gives you a more accurate month to month idea of actual tax expense) Or you can book it all one way or the other, then do 1 big adjustment at year end once you get the 1098. 

However, I notice that the FMV in your market is a lot closer to the listing and sales prices, which makes me think that the huge gap over here is just due to bureaucratic inefficiency and they'll become more accurate soon. 

Since banks will look at my mortgages but cannot count any rental income, my debt to income ratio is not accurate and my income is much lower as well according to their evaluation. 

@Nathan G. is pretty accurate on what he says .

Are your numbers and assumptions accurate?

Not only can they help provide insight to your market (may/may not be accurate information sometimes), but another person can also help offer objective views and push you when you're nervous to make a leap.

@Ryan Dossey do you find Skip Genie to provide accurate data?

Holding it and subsidizing the tenant's rent ($50 is NO cash flow) in anticipation of future appreciation is just gambling. 

You are not FORCED to buy a rent regulated building.If I am misunderstanding please correct me, but my interpretation is that any city, town or village within the state of NY can "opt in" to Rent Control at any time.So, when you say buying a RC building is a "choice" - I don't think that's accurate, since ANY municipality can opt in henceforth. 

Your response got me concerned that its a huge gamble and not worth the effort or risk.