Annual gross income is the amount of money you make BEFORE taxes. Your adjusted gross income is how much money you make before taxes, MINUS anything you can deduct. You can deduct many things, like student loan interest payments and alimony. So, you would have an adjustment if you paid for student loans this year. If your gross income (not adjusted) is $20,000 and you paid $1000 on student loan interest, your adjusted gross income is $19000. The IRS will then see your income as only $19000 instead of $20,000 and will tax you on that lower amount.
