Overall, the guarantor is applying for the apartment and must fill out a rental application, just like the tenant. Here, learn about application fees, tenant selection policy, security deposits, and other things to consider before applying to rent a place to live.Leap confirms the lease details with the building. The guarantor must have a gross monthly income of at least 3 times the monthly rent and must meet all other qualifying criteria. A guarantor is someone who cosigns the lease agreement. They are responsible for any rent payments that you cannot or do not make. They will typically be required to complete a rental application, submit income and financial documentation and undergo a credit check. If you are the guarantor or cosigner to a tenant, you must provide proof of income that shows your income is 5 times the monthly rent. Each applicant over the age of 18 that will reside in the home must complete an application.