Your Modified Gross Income isn't on your tax return, you need to calculate it starting with your AGI (Adjusted Gross Income) which is on the 1040 line 7.
"To calculate your modified adjusted gross income, take your AGI and add back certain deductions. Many of these deductions are rare, so it's possible your AGI and MAGI can be identical. According to the IRS, your MAGI is your AGI with the addition of the following deductions, if applicable:
- Student loan interest
- One-half of self-employment tax
- Qualified tuition expenses
- Tuition and fees deduction
- Passive loss or passive income
- IRA contributions, taxable social security payments
- The exclusion for income from U.S. savings bonds
- The exclusion under 137 for adoption expenses
- Rental losses
- Any overall loss from a publicly traded partnership"
https://turbotax.intuit.com/tax-tips/irs-tax-return/what-is-the-difference-between-agi-and-magi-on-your-taxes/L7kHckNS3