You must be the child's custodial parent to claim the credit for child and dependent care.
The IRS defines custodial parent as "the parent with whom the child lived for the greater number of nights in 2020. If the child was with each parent for an equal number of nights, the custodial parent is the parent with the higher adjusted gross income."
For more information, see IRS Pub. 503 - Child and Dependent Care Expenses
