Find this under Publication 503 for childcare credit:
You Must Have Earned Income
To claim the credit, you (and your spouse if filing jointly) must have earned income during the year.
Earned income.
Earned income includes wages, salaries, tips, other taxable employee compensation, and net earnings from self-employment. A net loss from self-employment reduces earned income. Earned income also includes strike benefits and any disability pay you report as wages.
Generally, only taxable compensation is included. For example, foreign earned income you exclude from income isn't included. However, you can elect to include nontaxable combat pay in earned income. If you are filing a joint return and both you and your spouse received nontaxable combat pay, you can each make your own election. (In other words, if one of you makes the election, the other one can also make it but doesn't have to.) Including this income will give you a larger credit only if your (or your spouse's) other earned income is less than the amount entered on line 3 of Form 2441. You should figure your credit both ways and make the election if it gives you a greater tax benefit.
So I guess the same would apply for both the child care credit and whether the childcare care expense can be excluded from income.
Thank you!
