Whether a duplex carries itself once the owner-occupant moves to the next house
Take a duplex bought a bit over two years ago, both sides identical two bed one bath. One side has been the owner's home the whole time, the other side rents for 1,300. PITI on the duplex is 2,180 with taxes and insurance escrowed. A common next step is buying a single family as an owner occupant with 5 percent down, moving in, and renting the duplex side out at 1,300 as well. That gets to 2,600 gross against 2,180 PITI, which looks fine until repairs or a month of vacancy come out of it. Say the next house is 340k with a rough PITI around 2,600 at current rates, against a 92k W2 income and 31k liquid, so 5 percent down plus closing leaves things thin. What matters most here is how the lender treats the vacated unit's rent. Practice varies: some lenders count the full projected rent, some apply a standard haircut of 25 percent for vacancy and expenses, and most want either a signed lease or, absent one, an appraiser's rent schedule before counting anything at all. The practical decision usually comes down to sequencing. Signing a lease on the current unit before there's a purchase contract on the new house means finding interim housing, while running both processes at once risks the timing not lining up. Getting the lender's exact rent treatment in writing early removes most of that uncertainty either way.
