From IRS Publication 503, Child and Dependent Care Expenses - https://www.irs.gov/pub/irs-pdf/p503.pdf
Is this your status? -
Generally, married couples must file a joint return to take the credit. However, if you are legally separated or living apart from your spouse, you may be able to file a separate return and still take the credit.
Legally separated. You aren't considered married if you are legally separated from your spouse under a decree of divorce or separate maintenance. You may be eligible to take the credit on your return using head of household filing status.
Married and living apart. You aren't considered married and are eligible to take the credit if all the following apply.
1. You file a return apart from your spouse.
2. Your home is the home of a qualifying person for more than half the year.
3. You pay more than half the cost of keeping up your home for the year.
4. Your spouse doesn't live in your home for the last 6 months of the year
