First I want to commend you on realizing that there is a cap expense and that if you do not attempt to estimate it across every month your not providing an accurate cash flow forecast. 

What I do is mid December I try to do my best to estimate my total year taxes, and then adjust the last quarterly payment to be a more accurate number... sometimes I get close, if I do not have time, I pay the suggested amount and deal with the residual in April.

How accurate are Credit Karma results?

I just want to properly calculate the Ratio and also factor in the # of occupants to get the most accurate number as possible. 

Almost seems like it would be “easier”/better to flip at the bottom of the market bc at least values have seemingly leveled out and you can gauge ARV more accurately at that point. 

We need to start getting some accurate building costs so we can decide which way to go.Thanks

Tax records have a way of being accurate because the county has a way of getting its money.

The only way to get a truly accurate number is to get the outstanding balance from the lender, which usually requires cooperation from the owner. 

He can tell you what accurate rents will be and can give you an idea of the rental needs/ demands are currently. 

Note to all that the map I posted above for DSM I do not believe to be accurate.