Your only income was $100? How were you and your child supported? Sounds like someone else can likely claim you and your child as dependents. You cannot get the child tax credit with only $100 of income --and you do not even say how you got the $100---did you work? The child-related credits are based on income from working. Not sure how $100 of income could make you head of household---since that also means you paid over half the costs of maintaining the household.