Software for engineers, operators,ysts, and developers working on land, sea, air, and space systems. Helping aerospace and defense organizations rapidly solve today’s most difficult engineering and mission challenges.. Adjusted gross income AGI is a measure of income calculated from your gross income and used to determine how much of your income is taxable. It is the starting point for calculating a filer’s tax bill in the United States and, among other things, is the basis for many deductions and credits.. Adjusted Gross Income AGI is defined as gross income minus adjustments to income. We suggest you refer to your federal income tax return to get a quick estimate of your AGI. On your return, please refer to Line if you filed a Form EZ..If your filing status changed from the previous year to “Married Filing Joint”, then each taxpayer will use their individual original AGI from their respective prior year tax returns. If the change is from “Married Filing Joint”, then both taxpayers will use the same original AGI from the prior year’s joint tax return..