earned income — includes wages, salaries, tips, and self-employment earnings.
qualifying child — a qualifying child for the earned income credit meets the relationship, age, and residency tests. A taxpayer who claims the earned income credit cannot be the qualifying child of another person. A person can be claimed as a qualifying child on one tax return only.
adjusted gross income — gross income reduced by certain amounts, such as a deductible IRA contribution or student loan interest"
Earned Income Credit — a credit that can be paid to low-income workers, even if no income tax was withheld from the workers' pay. To receive the credit, a taxpayer must file a tax return.