I assume this is a joint tax return being filed with a filing status of Married Filing Joint.
- Did both tax filers work *and* have taxable W-2 income in 2016?
- Was either tax filer self-employed, and after all the business deductions, there was no taxable business income maybe?
- If each tax filer received a W-2, did you correctly identify who each individual W-2 (or 1099-MISC if you got that) belonged too?
On a joint return, both tax filers are required to have "taxable" income, in order to qualify for the credit.
