Your qualifying dependent
Your dependent must be:
A child under age 13, or
Your spouse or another tax dependent (regardless of age) who is mentally or physically incapable of self-care
The expense must be work-related
The care must be for dependent care specifically, not your dependent's health care, and it must allow you (and your spouse, if married) to:
Work,
Look for work
Attend school full-time
Looking for work doesn't guarantee eligibility
If you spent the year searching for a job but never actually found one, and had no earned income for the year, the care expense doesn't qualify, even though you were technically looking for work while paying for it.
Who the expense can be for
The expense can't be for someone you claim as a dependent on your own tax return, or for your own child if they're under 19. The expense must be for one or more qualifying persons identified on your claim, and that person must live in your home for more than half the year.
Your filing status
You must file as single, qualifying widow(er) with a dependent child, married filing jointly, or married filing separately.
One expense, one benefit
You can't claim the same expense under both a DC-FSA and the Dependent Care Tax Credit. (See "DC-FSA and the Dependent Care Tax Credit.")