Looking for Lender in TN that can count rent towards DTI

[Eric C.]

I am trying to understand how buying a Duplex and counting rent of one side (currently leased at $1300 per month) would count towards offsetting of the mortgage for DTI. So for instance, on a 300k duplex with 20% down, at 4%, the PITI would be roughly $1400. So for DTI would $1400 be added to debt and $975 ($1300 x .75) be added to income, or would it be $425($1400-$975) added to debt for DTI purposes?