Assuming you're asking about tax year 2019: if the child lived with you and her father all of 2019, in the eyes of the IRS you are the custodial parents for 2019. The right to claim a child as a dependent belongs to the custodial (by IRS definition) parent , unless voluntarily relinquished.
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
