It is an oversimplification to characterize it in terms of who provides over half the child's support. Even if the grandmother provided over 1/2 the support, if the child was its mother's qualifying child (for example, lets say she worked, earned $1000, and could claim the EIC), the grandmother could not claim the grandchild's exemption regardless of the support she provided. There is no need for anyone to be head of household to claim a dependent exemption.

