Comprehensive guide on how to send a rental application denial letter. Your letter should have a professional and informative tone, covering exactly why you're denying their rental application.The letter will inform them why their application was denied politely. Inform your applicants of your decision with this straightforward, federallycompliant application denial form. This letter informs the tenant why they are being denied, and if there is any way that their application can be reconsidered. Lease Application Denial Letter Information: A Denial Letter is a formal way of informing a potential tenant that their application or tenancy has been denied.