converting primary to rental and purchasing new primary - DTI?

[Gloria Mirza]

I'm going to purchase a new primary residence in Feb/March of next year.  I know that my income will not qualify me alone.  Will I be able to count 75% of expected rental income for my old primary when calculating income?  Obviously I am living in my current primary and don't have any rental history for that house, but will rent it out after I close on the new primary.  

As background, I borrowed 75% of the home value in a conventional loan, 15% in a home equity loan, and have about a 90LTV.  I have 4 years of rental experience with other rentals that I own.