To determine MAGI, once AGI is determined, additional adjustments are made to add back certain deductions and tax-exempt income. Some common adjustments are IRA contributions, half of self-employment taxes, tax-deductible student loan interest, passive income or losses, rental losses, non-taxable Social Security benefits, and excluded foreign-source income, among others.There are many reasons MAGI is important in filing accurate tax returns and qualifying for tax credits and other benefits.