Subtracting $38,000 from my retirement accounts leaves $35,000 to use annually towards RE investing.

You then subtract out your loan that you have currently, and the remaining portion is what you receive back.Now, that's me answering your question though.  

Remember to add and subtract based on the comp; basement v crawl, garage v no garage, 1 car garage v 2 car, detached v attached.I use a spread sheet for comps.  

Subtract 18% or $248  from your present cash flow you will have a whopping $13 per month return on your cash invested. 

I expect how people are getting multiple properties while having mortgages is that the formula just adds or subtracts the final number as the rent coming in and the PITI is probably more than 38%.Thank you

It is subtracted from the NOI to get Cashflow!

We bought it for 37K and conservatively calculated an 11% ROI (that's before subtracting a mortgage payment). 

Safer to over estimate Depending on the area and person, some take gross rental income and subtract 25% for CapEx, vacancy, and prop management.So if your saying 2800 in income x 75% your left with $2100 I took the expenses you said and added them up.

After I’ve done the formula for how much I should offer for the tax delinq property; am I subtracting the amount of tax Owed from the offer price?

After I’ve done the formula for how much I should offer for the tax delinq property; am I subtracting the amount of tax Owed from the offer price?