Your MAGI (modified adjusted gross income) is your AGI plus certain deductions you must “add back.” These deductions include IRA contributions, student loan interest, one-half of self-employment tax, qualified tuition expenses, and more. Since the defined benefit plan does not provide a reduction of taxable income, as an IRA contribution would, there is not add back necessary to calculate MAGI.
https://turbotax.intuit.com/tax-tips/irs-tax-return/what-is-the-difference-between-agi-and-magi-on-y...
