Future rent from your brother usually can't be counted, though two program exceptions are worth checking. A parent co-signing carries real risk for the parent and very little for you. On the rent, the treatment depends on the program. FHA requires a documented two-year history of actually receiving boarder income, typically shown on your tax returns, so rent you expect to start collecting doesn't count there. Fannie Mae's HomeReady and Freddie Mac's Home Possible are the exceptions: on a one-unit primary residence they can allow boarder income for the purchase itself, with 12 months of documented shared residency and 12 months of the boarder's rent payments, capped at 30% of qualifying income (confirm current program requirements). Worth walking your specific situation through with a lender. And a separate note if you were thinking of adding him as a co-borrower instead: a recent job or industry change doesn't automatically disqualify his income. On the parent co-signing: for you as the primary borrower there's little to no downside. The exposure sits with the parent. They're fully on the hook for the debt, the loan lands on their credit, and when they later buy or refinance, the payment counts in their own debt-to-income unless they can document 12 months of on-time payments made by you, usually with canceled checks or bank statements from an account they're not on. That 12-month rule is exactly where co-signing goes wrong. We had a client with perfect credit co-sign for his sister; after her husband left and she missed three payments, the lates hit his credit and he couldn't refinance into a much lower rate when the chance came. Generous, yes, but a co-signer should go in knowing their finances are genuinely tied to that loan.