Here's everything you need to know about not returning security deposits, including a security deposit refund letter template. The letter should state whether the deposit is being returned in full, partially returned, or not returned at all.Learn the basics of how to write a security deposit letter to a tenant. The disposition letter is simply an accounting of how all or part of the deposit was applied. A security deposit return letter informs your tenants how much security deposit you will return. Read on for a free example letter. Any fee or deposit not designated as nonrefundable is refundable. A security deposit return letter informs your tenants how much security deposit you will return. Read on for a free example letter. Attach a copy of the permit, payment receipt, and any other documentation that will aid in the decision.