1. Before filling out a project application: Read and follow the NEAT Grants Program Booklet. Knowing how to write an in-kind donation letter for your nonprofit means understanding the do's and don'ts.Let's check them out! Gather all information required to complete the form. Have a valid form of payment. Include the nonprofit's EIN so the the donor can to check the charity's tax-exempt status with the IRS. Looking for an easy way to create fundraising letters? This guide and free templates empower you to effectively communicate needs and inspire support! To claim the tax credit, simply attach proof of the FloridaCommerce approved donation when you file your state tax return. An inkind donation is a noncash gift made to a nonprofit organization.