what purpose does magi serve 
the irs uses magi to determine whether you qualify for specific tax programs and benefits for instance it helps to determine the allowed amount of your roth ira contributions knowing your magi can also help you avoid tax penalties because over contributing to these programs and others like them can trigger interest payments and fines 8 your magi can also determine eligibility for certain government programs such as the subsidized insurance plans available on the health insurance marketplace 4