There are certain things that must be included or excluded from MAGI separate from adding back deductions. Income from tax-exempt interest, such as municipal bonds or certain savings accounts, as well as contributions made to traditional IRA accounts must be added back. If you claimed the foreign earned income exclusion, which allows a portion of income earned abroad to be excluded from taxation, add the excluded amount back to your AGI. There are other items that are required to be included or excluded based on the tax form and program you are using, so be sure to check the requirements.