You may be subject to both taxes, but not on the same type of income. For the Net Investment Income Tax, modified adjusted gross income is adjusted gross income Form , Line 37 increased by the difference between amounts excluded from gross income under section a 1 and the amount of any deductions taken into account in computing adjusted gross income or exclusions disallowed under section d 6 for amounts described in section a 1. Page Last Reviewed or Updated: Aug For example, the Code now requires over 50 other inflation-driven computations to determine deduction, credit and exclusion amounts in addition to the 50 separate computations needed to inflation-adjust the tax bracket schedules each year.