Must I be entitled to claim a child as a dependent to claim the earned income credit based on the child being my qualifying child?

No, you do not have to be entitled to claim a child as a dependent to claim the earned income credit (EIC) based on the child being your qualifying child. The support test for qualifying a child as a dependent does not apply for the earned income credit.

To claim the EIC, the child must meet the criteria of a qualifying child, which includes relationship, age, residency, and joint return tests. Specifically, the child must:

1. Bear a certain relationship to the taxpayer (e.g., son, daughter, stepchild, or eligible foster child).
2. Have the same principal place of abode as the taxpayer for more than half of the taxable year.
3. Meet certain age requirements.
4. Not have provided more than half of their own support for the year.
5. Not have filed a joint return with their spouse, except to claim a refund.

Even if you are not entitled to claim the child as a dependent, you can still claim the EIC if the child meets these qualifying child criteria. This is particularly relevant in cases where the custodial parent releases the claim to the dependency exemption to the noncustodial parent. The custodial parent can still claim the EIC if the residency and other requirements are met.

Sources:
Notice 2008-5
Publication 501 (2023)
CCA 200812024
§ 152. Dependent defined
Publication 596 (2023)