In my experience, the underwriting guidelines will consider 75% of the net rental income, as shown on 2 years' tax returns. If the rental income is newer than that, I think the underwriting becomes more nuanced, but it can still be used.
Debt-to-Income ratio will be a key factor. So in some sense, the income properties may "count against you" because of the debt they carry. The income will add to your income, but only at 75% of the net that you have reported.
Notice, this make it critical to be forthright on your tax returns if you intended to continue with leveraged acquisitions, including a primary residence.