Because Tax-Calculator itself does only static analysis of federal individual income and payroll taxes, it must interact with other models in order to analyze business taxes or conduct non-static analysis. These other models typically use Tax-Calculator to estimate reform-induced changes in after-tax incomes and marginal tax rates, and then use that information to calculate how other taxes or non-static behavior cause changes in individual incomes or expenses. These changes are then fed back to Tax-Calculator so that individual tax liabilities, as well as aggregate and distribution results, can be recalculated. All these interactions between Tax-Calculator and other models are handled by Tax-Brain.
The future development of Tax-Calculator itself will focus on the following activities: