You r child must live with your over 6 months. There is no 50/50 division of residence for IRS purposes. If the other parent claimed incorrectly, you will have to file by mail and let the IRS sort it out. Have on hand records that prove residency.
Head of Household
You may be able to
file as head of household if you meet all the following requirements.
- You are unmarried or considered
unmarried on the last day of the year. See Marital Status , earlier,
and Considered Unmarried , later.
- You paid more than half the cost of keeping up a home
for the year.
- 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.
Qualifying Person
See
Table
4 to see who is a qualifying person. Any person not described in Table
4 isn't a qualifying person
https://
www.eitc.irs.gov/eitc/files/downloads/f886-h-hoh.pdf
