Your daughter can NOT claim the child based portion of the EITC if you are claiming her child as a dependent.
"The EITC rules do not require the claimant to provide support, only residency". That's not exactly correct. I think what you may have heard of is "The EITC rules do not require the claimant to claim the dependent, only residency". That's true, but only in the case of divorced or separated parents. When the non-custodial parent is claiming the child as a dependent (and the child tax credit), the custodial (resident) parent is still allowed to claim the EITC. That special rule does not apply when the grandparent is claiming the child as a dependent.
Even if your daughter is claiming her child as a dependent; it would be far fetched for her to claim Head of Household living in your home. It's theoretically possible but It's a tough standard to meet and most living arrangements will not qualify. If it's family and not unrelated people, like 2 single moms sharing a residence, it's even more unlikely. If you try it, be prepared to prove it with detailed accounting records of household expenses.
@NCperson the age 25 rule does not apply if the mother is claiming a child as a dependent
