Does rental income from an ADU help me qualify for a mortgage?

Rental income from an accessory dwelling unit can help a buyer qualify for a mortgage, since many lenders will count a share of that income toward the buyer's debt-to-income ratio. Whether it counts, and how much, depends on the loan program, whether the ADU is legally permitted, and whether the income is backed by a lease or an appraiser's rent estimate. An ADU built without permits can complicate both financing and appraisal, so confirming its legal status matters before relying on that income. A lender can confirm the exact underwriting treatment for a specific ADU before a buyer counts on it.