Dependent of Whom?

Facts as I understand them:

1. Daughter is 16 years old
2. Due to family discord the child left the parental home (with parental consent) at the end of April 2022
3. The parents are married and live together
4. The child has lived at 2 separate locations in 2022 since leaving home. One location being her Grandfather's and the other a friends house.
5. As far as I know the child has not lived at any location for 6 months or more
6. The child has not provided more than half of her own support
7. The child earned less than $4,400 during the year
8. It is extremely unlikely the child will return to the parental home anytime soon

So, who, if anyone, is entitled to claim her as a dependent?

This, for some reason, has me baffled

Did anyone provide more than half of the child's support?

For anyone to claim her as a qualifying child, she must have lived with them for more than half of the year. If she hadn’t lived with anyone over half the year, she could be considered a qualifying relative of the grandfather if he provided over half of her support during the year (since he is considered a “relative that she doesn’t need to live with” based on the rules). The friend would not qualify since she must have lived with that friend for the entire year.

As far as I can determine no one had her long enough to provide over half of her support for the year. Basically, each location provided 1/3 of her support.

Take a look at IRS Publication 501 (https://www.irs.gov/publications/p501#en_US_2022_publink1000221013) and do a search for “Multiple Support Agreement”. This explains who can claim a dependent if no one meets the support test individually but would if combined with another individual who provided support.

As far as I can determine no one had her long enough to provide over half of her support for the year. Basically, each location provided 1/3 of her support.

This appears to be a big assumption on your part.

Who was paying health insurance? Her cell phone bill? Clothing? That stuff isn't dependent on which house she was in on a certain day.

You need to have a deep conversation with the client, and fill out the support worksheet that helps in situations like these.