Advance Search Instructions: After choosing the county in District of Columbia where your property is located you may add optional parameters . The more optional parameters you add the fewer appraisers you will find. Start off with broad parameters then narrow your search as needed. If you need a commercial or industrial appraisal, or a very specific type of appraisal it is better not to select a county, just add your parameters and let it search the whole state of District of Columbia for those types of appraisers.