If you're referring to the Child and Dependent Care credit reported on Form 2441, there's no minimum AGI to qualify -- you simply must have received earned income.
And, unlike most credits, there's not an upper limit at which the credit phases out. The Child and Dependent Care Credit gets smaller as adjusted gross income gets higher, but it doesn't completely disappear.
See the TurboTax blog The Ins and Outs of the Child and Dependent Care Credit for more information.
