If I already own a home, can I convert it to a rental instead of selling when I buy a new primary residence, and will the rental income (or a lease/deposit) help me qualify for the new mortgage?

Yes. You can keep your current home as a rental when you buy the new primary, and documented rent can help you qualify. There are two paths. If you qualify carrying both full payments on your income alone, the lender needs nothing about the rental at all. If you need the rent to offset the departing home's payment, you document it. How lenders count the rent: - New lease, conventional. With a signed lease plus an appraiser's market-rent report, Fannie and Freddie count 75% of the gross rent; the 25% haircut covers vacancy and maintenance. For a departing residence, what hits your ratios is that 75% figure netted against the home's own full payment (principal, interest, taxes, insurance, and any HOA). - Already on your tax returns. Once the property has rental history on Schedule E, lenders use the actual net rental income from the return rather than the 75% method. - FHA is stricter on a departing residence. FHA generally requires 25% equity in the home you're leaving, documented by an appraisal, plus the lease, before the rent counts (a relocation-distance exception exists). The math is where it gets tight. Rent often comes in below your current payment, and after the haircut that gap works against you in qualifying. It's still very doable, especially if you bought at a low rate and have meaningful appreciation since. Depending on how long you've owned the home, the lender may also ask you to document why you're converting it. These rules shift, so confirm the current treatment for your loan type. We can run your specific two-property numbers on the free Roadmap conversation.