If so, the correct formula for cash flow is:cash flow = rent / 2 - P&I paymentnotcash flow = rent - PITIor evencash flow = rent - PITI - PM charges.Many houses just don't work as rentals.You also wrote: "main issue told to me by the realtor and a few people who have made online inquiries about the house is the location".

specifically using the BRRRR formula.

They typically use some sort of formula based on square footage, condition, etc.

So the typical formula is 70 % of ARV- repair costs, but how do you factor in back taxes and liens...?

I win some, I lose some, instead of fighting someone else use your own numbers, if your numbers keep losing, then you may want to readjust your formula.

It will require lots of time and effort but will allow you to really understand a lot of the formulas and concepts in analyzing a deal.

Most of my work is formula driven, in understanding the costs, income, care level, demographics, employment challenges, location and more, I would love to connect with a group or owner who feels they are able to understand and provide a advantage or model for sucess.  

Think of the NOI as how much it costs to operate the property itself on an annual basis, barring catastrophic expenses.Now that you have your NOI and your Cap Rate, just plug it into the formula Offer Price = NOI / Cap Rate.

I am trying to figure out what formula to use in excel if I sold my note at a discount to calculate the new rate.

@Peter WentworthIn your formula, you need to deduct the following additional costs:1.