TAX_IDENTIFIER is a 100 alphanumeric field that displays the Miscellaneous Tax Identifier which 'identifies' a state's tax parameters used to provide additional information as supplied by the client or employee to calculate the taxes. 

These parameters often simulate information requested on the withholding certificate of the state. For example, FILINGSTATUS is a common Miscellaneous Tax Identifier. 

Tax Identifiers may be provided by the Tax Engine or the system and are used by [UPCALC] to calculate taxes.