If you are married filing separately, you can't take the credit.
If you are divorced or separated and sharing custody, you can't claim the child care credit unless you either
a) report the child as a full dependent because the child lived with you more than half the year and you are not sharing the dependent exemption with the other parent, or
b) report that you had custody more than half the year, but are not claiming the dependent because you released the exemption to the other parent.
If the other parent has already claimed the child as a dependent because the other parent has custody more than half the nights of the year, then you don't qualify to claim the child care credit, and your return is being rejected because you are listing the same dependent twice. Delete the dependent and remove the credit.
If the other parent did not have custody more than half the nights of the year, and is only claiming the dependent because you gave them a signed release form, then your return is being rejected because the other parent made a mistake and claimed the wrong dependent benefits for the child. You can print your return and mail it in, and the IRS will pay the credit, but they will also start an investigation of both parents to determine who can legitimately claim the child as a dependent.
