The declaration form requests a NAICS code or a brief description of the type of business. To calculate taxable value using the Personal Property Manual, the assessor completes three steps: â–« Select the appropriate expected life table,.To add a new business or change information regarding an existing business, a declaration form is available in our office. Obtaining a Declaration. Business Personal Property tax is an ad valorem tax on the tangible personal property that is used for the production of income. Taxpayers can complete transactions on MyTax DC or call 202-727-4TAX. You may now file your Personal Property Declaration online.