<< and claim head of household>>
note for HOH, there is also the 'supporting expense' rule. While the newborn satisfies item 3 below, there is still the open question of the expenses (#2) .....
Head of Household
You may be able to file as head of household if you meet all the following requirements.
1. You are unmarried or considered unmarried on the last day of the year. See Marital Status, earlier, and Considered Unmarried, later.
2. You paid more than half the cost of keeping up a home for the year.
3. A qualifying person lived with you in the home for more than half the year (except for temporary absences, such as school). However, if the qualifying person is your dependent parent, he or she doesn't have to live with you. See Special rule for parent, later, under Qualifying Person.
see page 8.
https://www.irs.gov/pub/irs-pdf/p501.pdf
it is possible, but may not that case here, that two unmarried people living together and neither qualify for HOH. Let's say She contributes more than 50% of the household expenses but HE has a child from another relationship. SHE would satisfy #2 but not #3 and HE would satisfy #3 but not #2. Both would file Single and HE could claim a dependent.
