Does rental income from a 2 family home help me qualify for a mortgage?

Rental income from a legal two-family home can count toward mortgage qualification once a lender verifies the unit is permitted and has a lease or market-rent estimate behind it. Underwriters typically count only a portion of that projected rent as usable income, and they confirm the second unit is legally separate before including it at all. An unpermitted unit usually cannot be counted, which surprises a lot of buyers. Have your lender confirm the treatment before you count on that income.