Last time I did any refinancing for my rental prop (2005) the lender considered my income from the rental at 75% of the actual rent charged.
I remember it being this way as far back as the mid-to-late 1990’s as well. I am sure some lenders were more lax than this the last few years, however, the 75% figure seems to be the amount used by traditional lenders/underwriters.
My guess is that any lenders who assume greater than 75% will have either gone out of business or tightened up their standards by now.
