Will I still qualify for the child tax credit if I am only claiming my dependent for half the year?

It is not possible to claim a dependent for half the year.   You claim the dependent for the whole year or not at all.  

@xmasbaby0  Can I claim a dependent for the entire year if I only provided care from Jan 1 - July 31 of the year?

The IRS considers the custodial parent to be the one with whom the child spent at least 183 nights in the tax year.  What's going on----are you and the other parent at odds over which one of you gets to claim the child tax credit?

No, not at all. I will be relocating and my niece who has been with me for 2 years will be going back to live at home. Just trying to figure out how to complete filing for next year and how that will play out with the upcoming CTC

Since the child lived with you for more than half the year and did not (I presume)  live with either parent for more than half the year, you can claim the child as a  dependent and the child tax credit.

 

As to the advance CTC payments, see https://www.irs.gov/newsroom/irs-announces-two-new-online-tools-to-help-families-manage-child-tax-credit-payments  

 

There are two types of dependents, "Qualifying Children"(QC) and standard ("Qualifying Relative" in IRS parlance even though they don't have to actually be related). There is no income limit for a QC but there is an age limit, student status, a relationship test and residence test. Only a QC qualifies a taxpayer for the Earned Income Credit and the Child Tax Credit. They are interrelated but the rules are different for each.

The support test is different for each type. The support test, for a QC, is only that the child didn't provide more than half his own support. The support test for a Qualifying Relative is that the taxpayer provided more than half the relative's support.

.A child closely related (niece counts) to a taxpayer can be a “Qualifying Child (QC)” dependent, regardless of the child's income, if:

1. He is under age 19, or under 24 if a full time student for at least 5 months of the year, or  is totally & permanently disabled.  She must be under 18 (for 2021) for the CTC. 
2. He did not provide more than 1/2 his own support
3. He lived with the relative (including temporary absences) for more than half the year
4. He is younger than the relative (not applicable for a disabled child)
5. If the child meets the rules to be a qualifying child of more than one person, you must be the person entitled to claim the child as a qualifying child (this essentially means that you have the parent’s permission to claim the child, if the child also lived with the parent more than half the year)
6. If the parents of a child can claim the child as a qualifying child but no parent so claims the child, no one else can claim the child as a qualifying child unless that person's adjusted gross income (AGI) is higher than the highest AGI of any of the child's parents who can claim the child.

See full dependent rules at: https://turbotax.intuit.com/tax-tools/tax-tips/Family/Rules-for-Claiming-a-Dependent-on-Your-Tax-Return/INF12139.html

@Hal_Al Thank you for this information! Answered my question plus a couple others.