I have formulas that easily does all the math and I track exact payments including any partials.

Each property's rent potential is estimated using our proprietary formula and the investment calculations are run for you, sending you a full financial proforma when it finds a match. 

Combined, that will put your DTI back in favor with the bank's "formula."

Does this formula work in reality?

I won't be able to get into the specifics too much with them right now, but am planning a mini-unit on real estate investing when we get to a relevant point in the curriculum (I'm going to use exponential functions/compound interest formula as a jumping off point).

I plug your place into my personal spreadsheet and I come up with cashflow of $323 based on the straight list price with the following assumptions:Expenses = $775 (my formula calculates this higher but that's a personal preference for a safety net)Tax = $3000 annual 30 yr mortgage at 5% apr and 20% downRent = $1700/mo

But there are always going to be a lot of houses of worship in Rockland County no matter what.One reason East Ramapo is in financial trouble is because the NY State funding formula is broken, not because of the school board.

Change is not always better...remember Coke tried to tell us New Coke was a better formula.

My Bank updates me QUARTERLY, which I deem sufficient for most scenarios.I agree with @Christopher Brainard, things like fixed or variable interest rate, and whether payments are interest-only, or interest-FREE, or uses the NORMAL (in this case 10 year) amortization formula (see link below), SHOULD be in the original Contract.https://en.wikipedia.org/wiki/Amortization_calcula...Regardless of all that, you (and everyone else) are always OBLIGED to provide a receipt for ANY goods or services upon payment - if requested!

An economic slow-down, a lost job, anything really, and the house of cards comes a tumblin down and you lose everything.BTW, I have the book in question and will check it out to see how the formula works.