A guarantor is a person or a company who will co-sign on your lease in case you do not qualify to rent an apartment in New York on your own. Your guarantor will fill out an application and provide similar documents to a landlord as you, including photo ID and recent bank statements.Fill out the lease guaranty application online and send us your paperwork. Here you'll find answers to the most frequently asked questions, downloadable forms to help you manage your lease, and essential telephone numbers. Guarantor should have basically all the same stuff that is requested of you. In most cases, guarantors will fill out the same application as a full lessee. The difference being that some landlords require only a credit screening.