Child & Dependent Care Credit with non custodial parent paying 100% expenses

Hello. I need help understanding the Child & Dependent Care Credit.
I am the custodial parent (children lived with me more than half the year), and the noncustodial parent paid 100% of the daycare expenses.
Under IRS rules, can either of us claim the credit using those expenses on Form 2441 or does no one claim it?
Where in IRS guidance or publications does it say this?