The most common reasons people don't qualify for the EIC are:
- Their AGI, earned income, and/or investment income is too high
- They have no earned income
- They're using Married Filing Separately
- Their dependent doesn't meet the qualifying child criteria (if claiming one)
- They're too young or too old (if not claiming a qualifying child)
There's a bunch of other qualifications that must be met. See the full list.