Certain states have maximum tax amounts that are normally based on the Unit Amount (unit price) of each item. Under certain conditions they may allow certain companies to base that maximum tax amount on the Invoice Total rather than the Unit Amount. This presumably is to facilitate invoicing components included in a single item subject to a single maximum tax amount. This check box on the DZ State Setup window provides a way for you to override the setting contained in the Rate & Boundary Database and base the maximum tax for all details in that state on the Invoice Total.

The field with this name in the DZ State Setup window is a Tax Detail Default.

DZ State Setup window