there are exceptions for MFS. from pub 503: Not legally separated.  You may also be able to claim the child and dependent care credit even though you aren't legally separated and you file a separate return. See the following examples. Example 1.  Amy separated from her spouse in March. She isn't separated under a decree of divorce or separate maintenance agreement and uses the married filing separate filing status. Amy maintains a home for herself and Sam, her disabled brother. Sam is permanently and totally disabled and unable to care for himself. Because Sam earns $5,600 in interest income, Amy can't claim him as a dependent (his gross income is greater than $4,150). And, because Amy isn't able to claim Sam as a dependent and she is still married as of the end of the year, she can't use the head of household filing status. Amy’s filing status is married filing separately and Sam qualifies as a qualifying person for the child and dependent care credit. Because of the following facts, Amy is able to claim the credit for child and dependent care expenses even though Amy uses the married filing separately filing status.