Hello Mike,
I just wanted to talk about DTI. All the calculations I've seen on here are accurate however I've personally seen approvals with DTI's as high as 49% back end.
Now as stated by another lender on this thread typically banks are going to be good at 45% back end and even more at 43% back end.
Fannie Mae uses a system called DU ( desktop Underwritter ) and this is a computer putting in various numbers from you 1003 application. If DU approves a loan at 47% then the loans is eligible for delivery to fannie or wells fargo or penny mac or whoever is going to buy the loan on the secondary market. The key is that you find a lender that has no overlays which means they follow fannie, freddie, FHA, VA, USDA guidelines. If you run into a bank that says you can't go over 43% DTI then they have overlays. If you run into a bank that says you need two years of rental history in order to use rental income they have overlays or aren't approved with Fannie. If you run into a bank that says you can't have more thank 4 financed properties they have overlays or aren't approved with Fannie. Overlays are put into place to protect the investor that is buying the loan or maybe the bank is holding the paper and they feel comfy with whatever their overlays are.
The next thing I want to chat about is the 2 year rule on rental income. I wrote a blog about this last week. Freddie Mac requires 2 years of rental history so if your mortgage guy/gal says he is going to run your file under LP ( Loan Prospector ) then you know that's the computer system Freddie uses to determine if you're file is accept or caution. If you don't have two years you're not going to get anywhere with Freddie products for rental homes. Or for using extra income to qualify for your primary or second home.
Now if your mortgage guy/gal says I'm running DU then you know it's a fannie program and Fannie Mae DOES NOT REQUIRE ANY RENTAL HISTORY. If you buy a house tomorrow and your renter paid you one month of rent for 1k then you can use 75% of that income right away.