Use Form RP524, Complaint on Real Property Assessment to grieve your assessment. The confidential income and expense data collected in the ASIE is used to improve assessed values of all properties similar to yours.The following answers to frequently asked questions may help you decide whether you should appeal your property's assessment and will guide you on how to do it. Qualified expenses must be equal to or more than the non-exempt assets. Here are some of the important tax exemptions you should know about if you own a home in Nassau County. Tangible Personal Property is everything that is not real estate (land, buildings and improvements). Question 20: I own a specialty property. I used to have to file on paper. In fact, Nassau County real estate taxes are among the highest in the country! (15) Signatures: Please ensure the application is filled out completely.