Learn the essential steps on how to add a cosigner to a lease to strengthen your rental agreement. My dad has agreed to cosign a lease with me but I am afraid my application will just be thrown out since I cannot provide a credit score or any proof of income.Cosigners and guarantors sign the lease with you and fulfill the purpose of taking responsibility for the monthly rent. A cosigner for an apartment takes on the financial responsibility for a lease. Learn how having a cosigner can help someone get approved for an apartment. Adding a cosigner is pretty straightforward with these steps: Do your research: Treat the apartment cosigner as an additional tenant. This guide will provide all the necessary information you need to screen, process, and add a cosigner to a lease. Cosigners are necessary for some lease agreements, particularly when an individual is a new or newly reformed renter. To cosign, the person must have a clean rental history and not have gone through any evictions. Cosigners sign the apartment lease with you, taking on the same financial responsibility as a tenant and then some.